Sheldon Cooper

thumb|220x220px|Sheldon with Amy in 2018
Sheldon LeeMiddle name revealed in "The Adhesive Duck Deficiency" Cooper,Pet name and family name first revealed in "The Luminous Fish Effect" B.Sc., M.Sc., M.A., Ph.D., Sc.D.,full list of degrees revealed in "The Love Car Displacement" is a Caltech theoretical physicist. Next to his best friend Leonard Hofstadter, he's the main protagonist of The Big Bang Theory and the titular protagonist of Young Sheldon.
Originally from East Texas, Sheldon started college at the age of 11 in 1991, receiving his first Ph.D. at the age of 16. As a kid, Sheldon was involved in numerous experiments as a "wunderkind," such as his plan to provide free electricity for his hometown by building a nuclear reactor - a plan that government pen-pushers stopped, claiming that it is illegal to store yellowcake uranium in a garden shed. Proudly geeky, he has no qualms about speaking Klingon, wearing vintage t-shirts sporting super-hero logos, or spouting various historical and cultural anecdotes (e.g., his account of the introduction of the fork into Thailand). While he may claim to be the perfect human specimen, Sheldon does have his faults. Sheldon is characterized by a strict adherence to routine and hygiene, an overly intellectual personality, a tenuous understanding of irony, sarcasm and humor, and a general lack of humility or empathy, the former of which is demonstrated in the fact that he has no problem voicing to his peers his admiration for his superior intellect. These qualities, along with his penchant for pranks, are his character's main source of humor. He is often considered to be the most iconic character of the show. Sheldon has developed a more sociable personality due to the influences of his friends especially his friend Penny and his wife Amy.
==Biography==
===Early life===
Sheldon was born alongside his twin sister Missy on February 26, 1980, in a Kmart in Galveston, Texas to the late George Cooper Sr. and Mary Cooper and was officiated at the Lawrence Memorial Hospital. He has an older brother named George Cooper Jr., who, along with Missy, is described by their mother to be "dumb as soup." Sheldon was raised according to his mother's Evangelical Christian doctrines, (i.e., learning how to pray and becoming the co-captain of the East Texan Christian Youth Holy Roller Bowling League Championship team and seven-to-twelve year-old division). Meanwhile, he was forced to watch football by his father.
Like any typical nerd, Sheldon was bullied a lot during his childhood, mostly because he constantly expressed intellectual superiority to his peers as he still does now. The bullying consisted of, but was not limited to, being beaten up, getting wedgies, being stuffed in small spaces, and having his personal belongings stolen. This is further accentuated when he tells Amy Farrah Fowler that the memories of his upbringing were tantamount to that of an insufferably tantalizing "hell." Further anecdotes also reveal that he built a so-called "Sonic Death Ray" that failed even to slow down the neighbor kids (all it did was annoy their dog), and constructed an armed robot using integrated circuits from ceramic semiconductor substrates cooked in Missy's modified Easy-Bake Oven, to defend his room from Missy (whose eyebrows were burned off as a result of a malfunction). Sheldon was also beaten up by his brother and sister, with Missy usually kicking Sheldon in his crotch and Georgie farting on his head while Sheldon tries to watch Star Trek. 
When Sheldon was five years old, his Pop-Pop died. Sheldon missed him and wanted him back and asked Santa to bring him back, but it didn't happen and this soured Sheldon so much that he disliked Christmas altogether. 
Since the age of 9, he had been dreaming about going to the Large Hadron Collider. (In "The Large Hadron Collision" (S3E15), he voiced those dreams.) Sheldon formerly despised birthday parties because he shared his birthday with his twin sister. Missy and her childhood friends tricked Sheldon that Batman was coming and he waited the whole afternoon at the door and all that came was a robin that flew in the window. He never wanted one after that, until his friends threw him an enjoyable birthday party in "The Celebration Experimentation."
As a kid, Sheldon wrote a paper entitled "A Proof That Algebraic Topology Can Never Have A Non-Self-Contradictory Set Of Abelian Groups" and his grade school science project paper, with the original title "A Rederivation of Maxwell’s Equations Regarding Electromagnetism," contains an approach that may change the way how ferromagnetic hysteresis is calculated. Despite his misgivings about being called a 'rocket scientist' as an adult, at nine years old, the boy genius wrote "Rocket Reentry & Retropropulsion" in a composition notebook; this provides the solution to the VTVL problem discreetly employed by Elon Musk years later for his successful SpaceX CRS-8 mission. While Sheldon audited Dr. John Sturgis' quantum chromodynamics course at East Texas Tech at 9, as Medford High School no longer academically challenged him, Sheldon formally entered college at 11. At 12, filled with disappointment at not receiving a titanium centrifuge to separate radioactive isotopes, he had to be flown to a hospital by helicopter to be treated for radiation burns following a mishap when he built a CAT scanner, which also resulted in the death of his sister's guinea pig, "Snowball." He also, at this time, conducted experiments involving the height of stairs only to deduce that if a step on a staircase is two millimeters off or more, a person is likely to trip - his findings are evidenced by his father breaking his clavicle. When Sheldon was 13, he attempted to build a nuclear reactor in order to provide free electricity for his town, but it failed after a government agent informed him that it was illegal to store "yellowcake" uranium inside a shed; he then erupted as a result. During that same year, he walked in on his father having sex with Mary who was roleplaying a german girl named "Helga", however, Sheldon thought that was another woman, and Sheldon decided to start knocking three times to prevent walking in on anything like that again. When Sheldon was fourteen years old, he graduated college East Texas Tech summa cum laude as Valedictorian, began graduate school at the California Institute of Technology, and was the youngest person at the time to receive the Stevenson Award at "fourteen and a half." He received his first doctorate at the age of sixteen, and he then spent four years on his second dissertation before obtaining his current position. 
In 1994, his father died due to a heart attack in "A New Home and a Traditional Texas Torture" (S7E12 YS). In "The Pancake Batter Anomaly" (S1E11), Sheldon said, at the age of 15, he got sick in Germany, and his mother had to fly back to Texas to help his dad at that time. This creates a continuity error in the episodes "The Thanksgiving Decoupling" (S7E9) and "The Proton Transmogrification" (S7E22) because Sheldon mentions to Bernadette's father Mike and to the ghost of Professor Proton, respectively, that his father died when he was 14.
When Sheldon graduated from college at 14, he got accepted into Caltech. Though he was planning to move in together with Tam, Tam found a girlfriend and decided to stay in Texas instead. This explains Sheldon not having spoken to Tam for a long time.
It's unknown when he moved into The Apartment Building with Sebastian before he drove him out, and he met Stuart Bloom and the comic book store.
In 2003, Leonard moved in with Sheldon after all his previous roommates could not stand him. 
=== Later life ===
A few minor details of Sheldon's later life have been revealed through his narration in Young Sheldon. In Vanilla Ice Cream, Gentlemen Callers, and a Dinette Set Sheldon states that he would have children whom he would draw up contracts with similar to the ones he'd made with friends and family over the years. At the end of Graduation, Sheldon mentions that he held a graduation party for his son Leonard, who was named after possibly after his best friend and roomate. Sheldon also mentioned he wanted to name him after Leonard Nimoy but Amy refused so they agreed to just Leonard. An argument between Sheldon and Howard in An Introduction to Engineering and a Glob of Hair Gel reveals that Sheldon never takes off his Nobel Prize so people will ask him about it. 
=== Career Highlights ===
Dr. Sheldon Cooper is a former senior theoretical particle physicist at the California Institute of Technology, focusing on string theory and its alter ego M-theory. He held this position for three-and-a-half years at the outset of the show and up until the eighth season. As he was being paid under a grant to specifically research string theory, he is then promoted to junior professor in order to change his field of study to dark matter, with the stipulation that he'd teach a graduate-level class on analytical mechanics. He returns to string theory research in the eleventh season. Previously, he was a visiting professor at the Heidelberg Institute in Germany at age fifteen and examined perturbative amplitudes in N=4 supersymmetric theories leading to a re-examination of the ultraviolet properties of multiloop N=8 supergravity using modern twistor theory at age sixteen. His doodle of a hyperelliptic Riemann surface was the basis of his postdoctoral fellowship. He believes string theory better unites quantum mechanics with general relativity than does loop quantum gravity. He neither gives credence to the notion that quantized space-time will manifest itself as minute differences in the speed of light for different colors (as he expects matter consists of tiny strings) nor that only loop quantum gravity calculates the entropy of black holes. Nonetheless, he is solely responsible for the university's six-loop quantum gravity calculations.
Sheldon's work on string theory is concentrated in several different directions. Notably, Sheldon has refocused his research from bosonic string theory to heterotic string theory. He wrote a paper on the decays of highly excited massive string states and illustrated mirror symmetry in the footnote of a publication. He determined that three-dimensional string-nets provided a unified picture of fermions and gauge bosons and reconciled the black hole information paradox with his theory of string-network condensates following a breakthrough in showing how neutrinos emerge from a string-net condensate. He also designated time for solving the space-time geometry in higher spin gravity and worked on time-dependent backgrounds in string theory, specifically quantum field theory in D-dimensional de Sitter space.
Moreover, Dr. Cooper's research spans particle physics in particle cosmology and studies the interplay between particle physics and cosmology during the Physical cosmology of the Universe. With Rajesh Koothrappali, he explored the Minimal Supersymmetric Standard Model, Theories of Supersymmetry breaking, string theory implications of Gamma rays from weakly interacting massive particles as dark matter annihilations, and considered Dark matter detection methods of optimizing a particle detector for 500 giga-Gelectronvolt Weakly interacting massive particles to this end. At a San Francisco conference, he tried to initiate a collaboration with Nobel Prize-winning physicist George Smoot by presenting him his paper on astrophysical probes of M-theory effects in the Chronology of the early universe. The famous physicist Stephen Hawking reached out to him during a lecture stay at Caltech after Sheldon's brilliant mind was revealed in a reading of his fascinating, though wrong, paper which posited that the Higgs boson is a black hole Entropy accelerating backwards through time. Sheldon also maintained a correspondence with cosmological physicist Elizabeth Plimpton for years about their mutual interest in effects of a passing gravitational wave signatures of inflations in the Chronology of the early universe. When Caltech received a new open science grid computer, he attempted to schedule a time to run computer simulations of structure formation in the early universe. He was thinking about how one could use the fact that a rapidly rotating mirror turns virtual photons into real ones as a method of observing dark energy. However, he no longer preoccupies his time with investigating why the Zero-point energy and predicted mass of the quantum vacuum has little effect on the metric expansion of space.
Sheldon has redirected his work to the nature of dark matter. In addition to studying the Weakly interacting massive particles as dark matter, a particle physics point of view, he also considered the scalar field dark matter, an observable large-scale structure of a geometric point of view. This led him to attempt a full mathematical proof of the Riemanni Penrose Conjecture.
Bridging theory and experiment, Sheldon is active in the field of particle physics phenomenology at high-energy colliders such as the LHC. Sheldon came close to figuring out why the Large Hadron Collider had yet to isolate the Higgs boson particle. Though, he was refused clearance for a very prestigious government research fellowship at a secret military supercollider, located beneath a fake agricultural station 12.5 miles southeast of Traverse City, Michigan.
In a similar capacity, Sheldon has made advances in theoretical plasma physics, studying turbulence and Turbulent diffusion, and how it might be reduced to improve fusion reactor designs. Consequently, Sheldon worked with colleague Barry Kripke on the Grant proposal for a new fusion reactor, as the university was only allowed to submit one proposal.
From nuclear physics, he was thought to have discovered a method for synthetic element. Despite the fact that a Chinese research team at the Hubei Institute for Nuclear Physics ran a test on a cyclotron with extremely promising results and reportedly found the element, his calculations were wrong; the table from the Handbook of Chemistry and Physics, in which he looked up the nuclear reaction rate rates of chemical elements such as mendelevium, was in units of square centimeters (cm2), which he misread as square meters (m2), meaning he was off by a factor of 10,000. Sheldon surmised there must be some atomic particle and molecular resonance between the elements he did not consider. In fact, someone from the Chinese research team added simulated signals to the data files, as Leonard Hofstadter re-ran the tests in his lab and disproved Sheldon's theory.
Sheldon additionally engages in condensed matter physics research on occasion and has lectured on topological insulators, as well as given a seminar on thermodynamic fluctuations. With Leonard, he co-wrote a paper titled "Paradoxical Moment-of-Inertia Changes Due to Putative Super-Solids", to be presented at an Institute for Experimental Physics topical conference on Bose-Einstein condensates. He discovered that electrons traveling through a graphene sheet on hexagonal pathways possess zero effective mass since they coincidentally exhibit the same dispersion pattern as Dirac fermions and must be considered as a Fermionic field wave. In addition, he had a minor epiphany regarding the polymer degradation phenomenon.
From a philosophical perspective, Sheldon has grappled with Gedankenexperiments (i.e., "thought experiments") to illustrate the quantum measurement problem. He produced four out of the five Gedankenexperiments he thought necessary for a cogent restatement of the quantum measurement problem, before the information was lost.
For his contributions to theoretical physics, he won a Caltech Chancellor's Award for Science. In "The Monopolar Expedition", Sheldon received a grant from the National Science Foundation (NSF) to lead an expedition to the Magnetic North Pole in the Arctic Circle for a magnetic monopole experiment in search of slow-moving magnetic monopoles, with Leonard, Raj and Howard as his support team. In the experiment, he detected what he believed was a significant magnetic monopolar magnetic charge, validating string theory, one of the chief predictions of superstring theory. Though Sheldon publicly announced he had confirmed string theory and would receive a Nobel Prize, he learned that the charge detected was actually static electricity from the others' electric can opener, forcing Sheldon to issue a retraction to his announcement and severely damaging his reputation at the university. Soon after, National Public Radio with Ira Flatow from Science Friday interviewed him by phone from his office, regarding the recent so-called discovery of spin ice and magnetic monopoles in spin ice. Based on his supposed discovery of a new stable superheavy element (which was actually a blunder), Sheldon appeared on Science Friday twice wherein a possible Nobel Prize in Chemistry was mentioned, had an article written about him in Physics Today and the National Science Foundation (NSF) wanted to give him a substantial grant.
Based upon a theory from Leonard, Sheldon wrote a paper detailing a theory that space-time is like a super-fluid. The paper was well received by the scientific community that included Professor Stephen Hawking. 
In "The Anxiety Optimization", Sheldon is trying to increase his working efficiency by keeping a high anxiety level while driving everybody crazy. The only good point is that he wants his friends to annoy him. Extremely tired, both Penny and Leonard put him to bed singing "Soft Kitty".
Leonard gets an idea to compare the universe to the surface of an Nth dimension sphere which he describes to Sheldon, who finds the theory interesting. He works out the math. Together they are praised, lecture on their discovery and get an award. Howard comes up with the idea to turn it into a working guidance system which is patented, and Howard builds a working prototype by the end of season 9.
In the 11th and 12th seasons, Sheldon and Amy work together on a Super-Asymmetry for string theory which is published and widely applauded. After a couple of Fermi-Lab scientists accidentally prove their theory, all of them are in competition for a possible Nobel Prize.
In "The VCR Illumination", after Sheldon finds the Russian paper that says the Super Asymmetry is not worth pursing, both he and Amy get very depressed. Sheldon locates an emergency VHS tape made by him when he was eleven (for, according to him, the day they stopped making Star Wars movies). His character from Young Sheldon tries to give him a pep talk but it was recorded over by his father with one of his football games. Amy keeps watching it and then finds his father's halftime pep talk which does help Sheldon. His father tells the team that they're not going to win this game, but that that does not make them losers. They can learn from failure as much as they can learn from success. Sheldon is encouraged and even thanks his dead father in the end.
In 2019, both he and Amy accept the Nobel Prizes in Physics for the development of Super Asymmetry. At the ceremony, Sheldon puts aside his self-centered speech and realizes that his achievement isn't just his but also his family and friends who encouraged him and tolerated him. Sheldon introduces his friends to the world and tells them how much he loves them, even calling him his other family, in the last moments of the show.
== Series Overview ==
=== The Big Bang Theory ===
==== Season 1 ====
Sheldon and Leonard need to get a Fractional T1 Bandwidth Connection, they decide to finance it by going to a sperm bank; however, they change their minds because Sheldon thinks that they are committing genetic fraud. Back at their apartment, they meet their new neighbor, Penny and try to get her stuff from her ex-boyfriend, Kurt, who takes their pants. (Pilot)
Sheldon goes to Penny's apartment to clean what he finds is a mess. Leonard Comes to tell him not to, though follows Sheldon in his cleaning and Penny gets mad at them. Leonard tells Sheldon say sorry, though he doesn't do well and Leonard has to go over personally and get help from Raj to forgive them. She says she's happy with Sheldon and Leonard cleaning her place. (The Big Bran Hypothesis)
Sheldon and his friends are going to Penny's Halloween party, all wanting to dress up as the flash. Leonard decides they all have to change and they all agree. During Penny's party, her boyfriend Kurt comes and Leonard provokes him, resulting in Sheldon getting terrified as Kurt lifts Leonard. As a tipsy Penny's emotions surface, Leonard comes to comfort her and he taunts Kurt. (The Middle-Earth Paradigm) 
Sheldon finds out Penny's whole family got sick over the weekend and starts to panic. The next morning he wakes up sick and Leonard runs to spend time with his friends. He misbehaves in The Cheesecake Factory and Penny takes him home. She ends up irritated with him and mad at Leonard, who she leaves to take care of Sheldon. Sheldon eats grilled cheese while Leonard sits with him, having gotten a concussion. (The Pancake Batter Anomaly)
Sheldon meets a kid genius named Dennis Kim, who Sheldon hates because of him outstripping all his achievements. He ends up bothering all his friends and they do everything they can to make Dennis lose focus. They succeed, though Sheldon feels 0 pity. (The Jerusalem Duality)
Sheldon and his friends have The Physics Bowl Quiz to compete in. They kick Sheldon off the team for ruining the fun and challenge in the game and Sheldon forms his own team while they recruit Leslie Winkle, Sheldon's nemesis. Sheldon and his opponents meet a stalemate in a question and Sheldon's pride costs him and his team their victory. (The Bat Jar Conjecture)
Sheldon's sister Missy comes to visit and Sheldon's friends start to compete to date her. Sheldon's caught by Missy and Penny making Leonard a deal to eat cheese without farting to sleep with her leading to a talk with the twins. She kicks Sheldon in the groin and Sheldon tells his friends in pain that her life is her decision how to live. While Missy heads back home, she and Sheldon make up, though Sheldon's not happy she tells people he's a rocket scientist. (The Porkchop Indeterminacy)
Sheldon and Raj are having a game of Tetris and arm wrestling which ends in a tie once Sheldon's losing in Tetris, though Raj lacks strength. Penny tells them to stop and learns Leonard's never celebrated his birthday, to which she blackmails a reluctant Sheldon to help organize Leonard a party. Sheldon and Penny go shopping to get Leonard a present and Sheldon pretends to be an employee at the store they go to. When Leonard gets back home, he missed his party, having had to take care of Howard, who was planning to surprise him. (The Peanut Reaction)
==== Season 2 ====
Sheldon's uninterested in Raj and Howard's activities, which he tells Leonard once the former wonders how he could let them act so inappropriately. Penny asks Sheldon to keep a secret, which he struggles with. He moves out of his apartment, though Raj and Howard kick him out and send him back to Leonard, who he accidentally reveals the secret to while under the influence of funny tasting milk Howard gave him. Leonard then insults Penny and finds a camera on the way back to his and Sheldon's apartment. (The Bad Fish Paradigm)
Sheldon gets Penny into an addiction to Age of Conan, which she constantly bothers him to get help with. Sheldon threatens Leonard to take action or he'll be very hard for Leonard to live with. Eventually, Howard, who Penny tends to find disturbing successfully gets her to stop. (The Barbarian Sublimation)
Sheldon bans Penny from his apartment for her infractions and defiance. The two eventually engage in a war of strikes and Sheldon forces Penny to struggle to reclaim her clothes. His refusal to compromise leads the tension to grow til Leonard helps Penny contact Sheldon's mother, who forces him to forgive Penny and surrender. (The Panty Piñata Polarization)
Howard designs M.O.N.T.E. for him and the guys to win a competition. When Penny comes over, Howard's perverted nature causes her to snap and send him into a depression, costing Leonard, Raj and Sheldon a valuable teammate against Kripke. The three guys watch videos of the Kripke Krippler and witness the machine's extreme power and Sheldon's overconfidence in battle gives Kripke a swift upper hand as the guys lose the match and M.O.N.T.E. Howard, who Penny punched finds the robot's gone and Penny sends Sheldon into a depression too. (The Killer Robot Instability)
Sheldon goes to the North Pole to prove String Theory and brings his friends with him. Howard's very reluctant, while Raj and Leonard are willing to go through some pain for gain. The season ends with Sheldon looking forward to the next 3 months in the North Pole.
==== Season 3 ====
Leonard gets mad at Sheldon and Howard when Howard leads Sheldon to inappropriately discuss Penny and Leonard's sex life in front of them. He makes a bet with Howard and meets Professor Crawley, who reveals Howard's right, forcing Sheldon to give up one of his comic books to him. The episode ends with Sheldon making Leonard mad once more. (The Jiminy Conjecture)
Once Raj faces deportation, Sheldon forces Raj to either work for him or be deported back to India. As Sheldon and Raj work, they eventually start fighting and Raj quits. The episode ends with Sheldon giving Raj a second chance to work for him and they walk together as the "Eye of the tiger" theme plays.
Sheldon's at his computer while the guys play Mystic Warlords of Ka'a and Sheldon reveals a talent of his to Penny. He goes into a tournament with Raj to get even with his mortal enemy Wil Wheaton. Wheaton deceives Sheldon to make him forfeit the game, then reveals his grandma's alive seconds prior to defeating Sheldon and Raj with Stuart Bloom on his team. (The Creepy Candy Coating Corollary)
The guys are going kite fighting with a wager of kites and Howard's obsession with hot girls costs him and Raj their victory and Raj's kite to Sheldon and Leonard, leading to a dispute between Howard and Raj. With Leonard expressing an interest in football, Sheldon reveals he knows the sport cause his dad made him watch football games prior to doing homework. Sheldon Makes Cylon Toast and runs out of bread, leading him to go get bread from Penny. He gives more hints about football without thanking Penny. Penny convinces Leonard to go fly kites with Sheldon in Leonard's last scene in the episode. (The Cornhusker Vortex)
While solo in his own apartment, Penny has an accident and dislocates her shoulder. Sheldon comments there wasn't a shower mat or adhesive ducks to help her not get hurt. She foolishly tells Sheldon to help her, not realizing that an ambulance would've helped her MUCH faster and he dresses her up while peaking at her secretly. While filling out a medical form for Penny, Sheldon makes her mad and Sheldon writes down she has episodes of extreme rage. He then takes her home under the influence of powerful pain medication and they sing soft kitty together.
Howard finds out the day Sheldon drove Penny once she broke her arm, he drove through a red light and is scheduled to appear in court the day the guys are supposed to see Stan Lee in Stuart's store. Sheldon's mad at Penny for making the guys miss seeing Stan Lee, though Raj, Leonard and Howard reveal they're not going with Sheldon to his trial. As Sheldon starts preparing his speech for court, Howard says Sheldon's going to jail. When Sheldon objects to paying and proceeds to insult the judge, he denies the chance the judge gives him to say sorry and he gets put in a cell, where he tells a cellmate he has a spot. Once he finds out he has to pee in front of a cellmate if he has to pee, he decides to tell the judge sorry and is let out of jail. Upon Howard teasing Sheldon via mentioning he, Stuart and Leonard went for gelato with Stan, which he said they could call him, Sheldon gives Penny the moving finger and goes. Penny gets Stan's address from Stuart in exchange for going to his cousin's wedding with him and she gets permission to bring Leonard, who Stuart will tell people is Penny's cousin. Penny does most of the talking and Sheldon's lack of understanding sarcasm leads him to go into Stan's house and Penny runs once Stan gives orders to have the police called. Sheldon gets a restraining order, which he's proud of and says he'll be seeing Stan once more at the hearing while going to place his new restraining order near an older one. (The Excelsior Acquisition)
Sheldon pesters Leonard relentlessly when he chooses to take Penny rather than him to Switzerland. Eventually, Sheldon and Penny end up in a tie when they get sick and Raj goes with Leonard, with incredible excitement and joy. (The Large Hadron Collision)
Sheldon meets his future wife Amy Farrah Fowler when Raj and Howard blackmail Sheldon, though they quickly start regretting their decision to unite them. (The Lunar Excitation)
==== Season 4 ====
Penny drives Sheldon and Amy on their first date to a restaurant. Penny threatens Sheldon, who decides to cancel plans as a result, which he tells Leonard, who finds out that the Wolowitz Programmable Hand, which trapped Howard's penis when he made an effort to masturbate earlier in the episode, just happened once more. (The Robotic Manipulation)
Sheldon wants to transfer his conscience to a robot, leading him to change his schedule and make a Mobile Virtual Presence Device to dodge the dangers of the world. He wants to see Steve Wozniak in The Cheesecake Factory, though hurts himself. Penny sings him Soft Kitty as Sheldon plays his flute. (The Cruciferous Vegetable Amplification)
Sheldon and Amy have a disagreement, putting their relation on hiatus. Sheldon picks up cats to replace her and Leonard phones Mary Cooper to help Sheldon. She has Amy come over and both compromise, leading to a reunion. (The Zazzy Substitution)
Sheldon and Raj have a fight, which ends in Sheldon's victory and Raj unhappily vows revenge. (The Hot Troll Deviation)
Sheldon's the travel supervisor during the group going to a hotel in San Francisco to participate in a science conference. He has Leonard drive the lead car with him in the front seat, Penny and Amy in the back. When Penny gets competitive with Sheldon, he sends her to the other car, which she and Raj don't enjoy. Howard meets Bernadette's ex-boyfriend and former prof Glenn and starts acting up in front of Bernadette, leading the group to an unpleasant and chaotic night. The next day at the science conference, most of the discussion is arguing and they go back home unhappily, without Penny, who left with Glenn. Once no one guesses in Sheldon's game of I-Spy, he mentions he saw a police car and Leonard's pulled over offscreen for speeding. (The Love Car Displacement)
Sheldon calls the police cause his World of Warcraft account was hacked. Leonard's baffled he'd be so dramatic and Sheldon tells him the FBI hung up on him. He recruits Howard and Raj in a fit of fury and desire for justice on the hacker. Sheldon gives Howard a rare praise for finding the hacker, Todd Zarnecki and the men prepare to confront him. He handles them in the first encounter, though once the guys call Penny for backup, she kicks him in the groin. Sheldon celebrates over their success, to which everyone looks at him cause Penny did the main job. Sheldon says he said we. (The Zarnecki Incursion)
==== Season 5 ====
Leonard calls off his friendship with Sheldon when Sheldon's ill mannered and annoying tendencies are too much for him. Eventually, Sheldon's care for Leonard causes Penny to sympathize and Leonard decides to reunite with Sheldon, who reveals he pulled the main breaker switch that led to a power outage. The episode ends with Howard getting the astronaut nickname "Fruit Loops". (The Friendship Contraction)
Sheldon's barber gets sick and he starts to act weird. He gains an addiction to bongos, disrupting Leonard and Penny's sleep and he falls down the stairs while playing his instrument. Eventually, Penny cuts his hair once Amy persuades him to accept her gesture and she accidentally cuts more than she should, which he doesn't notice. (The Werewolf Transformation)
Sheldon's a Reverend at Howard and Bernadette's Wedding with Raj, Amy, Leonard and Penny. He makes several recommendations prior to the wedding for a location and asks Leonard about his visions of marrying Penny, which Leonard doesn't like. When his time to speak comes, he speaks Klingon, which Bernadette told him was forbidden. He reluctantly complies, at a cost. He takes Amy's hand, impressing her as Howard goes to space. (The Countdown Reflection)
==== Season 6 ====
Sheldon hires an attractive grad student named Alex Jensen, who concerns Amy, til Penny ends up with those concerns. Alex Hands him yogurt in the cafeteria, where Sheldon is disappointed, though forgiving that she didn't remove the bottom cherry stem, which Sheldon chokes on. Alex Expresses an interest in Penny and Sheldon tells Alex to focus. (The Higgs Boson Observation)
Sheldon has a fight with Howard over a parking spot, which escalates to their partners. Eventually, Sheldon temporarily lends Howard the spot and everyone reconciles, though Penny isn't happy, as she was injured by Amy, who was swinging to attack Bernadette when the latter ducked. The episodes ends with Sheldon taking his cushion for inspection and cleaning and talks inappropriately with the person in the store. (The Parking Spot Escalation)
Sheldon makes Alex uncomfortable when he has sexual discussions with her and she complains about him. He talks inappropriately to Janine Davis, head of Human Resources and gets all the guys to join him in her office. He then continues to make extremely inappropriate comments to her. Despite apologizing to Alex, he forces her to do his work for her and get top scores. (The Egg Salad Equivalency)
==== Season 7 ====
Sheldon's sister Missy Cooper gives birth to a baby boy and Sheldon's not enjoying the time there. Sheldon's friends imagine their lives without him, with Stuart getting rejected from all scenarios and wanting to get in. The episode ends with Stuart eating solo in The Cheesecake Factory. (The Cooper Extraction)
Sheldon goes on a double date with Amy, Howard and Bernadette, though meets a guy named Eric who he pays more focus to than Amy. Sheldon Kisses Amy and they go see a 9 fingered banjo player, where Eric comes to join them. Upon returning home, Sheldon mentions to Leonard that he was displeased the banjo player was missing a finger, though his can do attitude made up for that. (The Locomotive Manipulation)
Sheldon Learns his childhood idol Professor Proton died and acts like he's ok with the news, though his emotions start swirling up during a debate with Howard and Raj on what order to watch the films in. He spends a lot of the day having dreams of his old friend and receives comfort from Leonard. The episode ends with Sheldon receiving a message from Arthur's ghost. (The Proton Transmogrification)
In the season finale, Sheldon struggles with President Siebert's refusal to let him change his field of study and Leonard's plans for a new life with Penny. He has a talk with Amy, who he snaps at and finds Stuart's store burnt down. He snaps at Stuart too, deciding to leave the city. Leonard, having not seen him longer than normal goes to find him and wishes him well with Penny and Amy attacks Leonard with a pillow for letting Sheldon leave.
==== Season 8 ====
Sheldon gets more serious in his relationship with Amy, even admitting that he loves her ("The Prom Equivalency"), and secretly revealing a family engagement ring ("The Commitment Determination"). Sheldon also creates a new scientific theory with Leonard and begins his studies on Dark matter. Amy breaks up with Sheldon while Sheldon asks Gollum what to do with the wedding ring he was about to give to Amy.
==== Season 9 ====
Sheldon's deeply hurt that Amy split with him and tells Leonard not to get married as a result of his own pain with separating from Amy, though changes his mind out of anger at her. He meets up with her and they go to the Wolowitz house to watch the wedding. While watching, Sheldon insults Amy and she decides to split with him. He tells his mother the issue and she tells him to keep his engagement ring, cause Missy's married and she doesn't like her older son's girlfriend. Post finding Leonard upset, he goes to Penny, who has a talk with Sheldon. She eventually says Amy's issues with him aren't her fault and he leaves. The episode ends with Sheldon talking to Leonard about the advantages of male over female. ("The Matrimonial Momentum")
While Amy is having date night with Dave, Sheldon comes in and finally proposes his love to her. Dave then makes Sheldon take the hint and says "Kiss her, you brilliant fool!". Amy and Sheldon both kiss and they both finally are back together. ("The Earworm Reverberation")
In the next episode "The Opening Night Excitation", Sheldon has coitus with her as his birthday present to her, it later on becomes a tradition.
Sheldon's friends discuss his birthday and Sheldon vanishes. Sheldon mentions his issues with birthdays and his friends cheer him up, leading Sheldon to reluctantly agree, claiming Amy owes him big time. Sheldon discusses his birthday cake wishes with Penny's Posse and what kind of music he likes. Once Sheldon comes to his apartment to have his party, he gets stressed and runs to the bathroom. He mentions more of his issues to Penny and apologizes to his guests, expressing his appreciation for their presence. Sheldon of course disrespects Howard and Raj and has Stephen Hawking sing to him. Hawking reluctantly agrees to sing with the group while incomplete and they sing happy birthday to Sheldon. He blows out the candles and Adam West asks who's taking him home. (The Celebration Experimentation)
Sheldon Hires Stuarts to spend a day with Amy while he goes to a film screening. Stuart's rejected by Amy in everything and Sheldon has to do things personally, so he pays Stuart to hold his spot in line. When someone else goes to join their friends, Sheldon makes a scene and quotes Rosa Parks, eventually getting convinced by Leonard to stop. (The Line Substitution Solution)
In the season finale, Leonard mentions the scene Sheldon made at the film screening to Penny while they have a debate about a 2nd wedding ceremony. Sheldon Displeases Penny shortly post coming back to his apartment, mentioning he's inviting other people to her and Leonard's wedding ceremony and Sheldon says he's a part of the thing too. When Amy drives to pick up Sheldon's mother from the airport, Sheldon spends most of the time having the conversation one sided or getting sarcasm. Sheldon's mother isn't happy that Beverly's coming and the 2 aren't too happy to see each other, causing Amy and Penny discomfort. Sheldon does what he can to break the ice and Leonard brings his father. Amy drives the car as Sheldon gets uncomfortable with Mary and Alfred connecting. Amy sees better than Sheldon what's happening and upon coming back home, Penny bursts out laughing as Sheldon and Leonard can't get in touch with their parents.
==== Season 10 ====
Post an awkward night, Sheldon has fears of his mother marrying Leonard's father. Leonard and Penny do everything they can to tell him to go to sleep, though he continues to talk and the next day's not much better. He and Beverly for the first time ever snap at each other and Sheldon talks very inappropriately to Leonard's father about if he and Mary had a sexual relation once they left dinner. Sheldon decides to find out how to pair the five adults, though Amy comes in, enthusiastic for Leonard's wedding. Sheldon tells Leonard at the wedding how much he means to him, though continues to make unacceptable comments, which repulses Alfred, though Beverly chuckles. The episode ends with Sheldon in the back seat, disrespecting his mother.
Amy's apartment needs fixing for five weeks and she decides to cohabitate with Sheldon in the meantime. Sheldon's reluctant, though some persuading from Penny, Leonard and Amy convinces him. Sheldon and Amy go to Penny and Leonard for help on how to cooperate. Sheldon gives Amy a difficult night, as she can barely sleep for more than a few minutes with Sheldon's frequent yawning and talking. She and Sheldon discuss the difficulties of living together and go back to their apartment post a weird quarrel. Penny tells Leonard their neighbors are weird. (The Cohabitation Experimentation)
Having had a long night, Amy and Sheldon struggle with how to live together. Sheldon goes in Penny's car to talk to her about the difficulties of living with Amy and eventually, Penny connects when she says she has the same issues with Leonard. The two friends go out for ice cream and Sheldon explains his reason for knocking three times and his insecurities of his relation with Amy. Once Sheldon returns home, he apologizes for his behavior, finding his seat warm. He then proposes to share a toothbrush holder with Amy and she accepts. (The Hot Tub Contamination)
Sheldon and Amy decide to hold a brunch and invite their friends over. Sheldon, scared of the pop, spends 15 minutes to open a bottle. The pop scares him, despite him knowing of said pop. Stuart comes to the brunch and Sheldon displeases him by mentioning the visitors are their practice round. As Stuart gets increasingly unhappy, he eventually near leaves til Sheldon decides to make up for his behavior and apologizes. While drunk, the men praise each other and ignore Amy, who's cleaning on her own. (The Fetal Kick Catalyst)
==== Season 11 ====
In "The Proposal Proposal", Amy says yes and Shamy becomes engaged as they start to plan their wedding.
Sheldon goes with Leonard to Texas to settle a feud with George Cooper Jr., Sheldon's brother. Sheldon goes to George's tire store where Sheldon sees his brother for the 1st time in years. Eventually, post a number of arguments, the two brothers make up and George agrees to go to Sheldon's wedding. (The Sibling Realignment)
The couple was married in "The Bow Tie Asymmetry", Sheldon and Amy make a big breakthrough and they begin working on their Super-Asymmetry Theory together.
==== Season 12 ====
Sheldon has his honeymoon with Amy, though things get rocky with Sheldon's quirks and inappropriate comments. Sheldon brings Amy and himself a hot dog and mentions his insecurities about their marriage. They compromise and make up, with Sheldon's last scene in the episode having him tell Amy to tell him The randomness is not really genuine because ...”the true randomness of numbers is an unsolved problem in computer science” while she's naked. (The Conjugal Configuration)
Sheldon's childhood friend Tam Nguyen wishes to get in touch with Sheldon, who feels betrayed by him. Early in the episode, Leonard mentions that Sheldon made the same accusations to Tam that he did to an imaginary koala. Sheldon eventually makes up with Tam, though calls Leonard his "California best friend" and leaves as Leonard goes to drive Tam to the airport. (The Tam Turbulence)
Howard dresses up as Sheldon for Halloween, which offends Sheldon and he dresses up as Howard in retaliation. Once tensions settle, Sheldon, Howard, Leonard and Raj watch "Halloween", which Sheldon doesn't wanna watch. He pretends to be disappointed when Amy comes to get him out of the film and is displeased with her for taking a long time. (The Imitation Perturbation)
Sheldon and Amy are still upset about their theory getting disproven and find Leonard and Penny are making rules as to unacceptable topics with the couple. When Bernadette says they're doing "nothing", Sheldon starts to get distraught and says his career's come to nothing, storming back to his apartment in a fit. Sheldon's tantrum worsens over time, engaging in weird behaviour and calling tea "leaf soup". Leonard and Penny talk to Beverly, who displeases Leonard via having time once the issue regards Sheldon. When Leonard and Penny mention Beverly's advice, Sheldon says things near word for word to Leonard that Beverly said to him. They throw the paper in fire and burn the shower curtain. When finishing a VCR taping that Sheldon made as a kid which his father filmed over, his late dad's words persuade Sheldon and Amy to get back on their feet. (The VCR Illumination)
Sheldon meets up with the last guest star of the show, William Shatner, on Wil Wheaton's Professor Proton science show. During Sheldon's excitement, he ends up puking on Shatner. When Wil hosts the last Dungeons And Dragons game of the show, the girls ironically know better than the guys why Stuart rather than them got the invitation to play with Wil and the celebrities. Once Leonard's kicked out of the game, the guys go to join his game, though an unhappy Wil says he's sick of them using him to see his famous friends. When Sheldon blows things, Wil and the ladies send the guys a photo to taunt them. (The D & D Vortex)
Sheldon And Amy have supper with Drs Pemperton and Campbell, where Amy says she's sorry for her tantrum and when Pemperton says her comments were hurtful, Sheldon offends them. Tensions escalate between the 2 parties and Siebert tells them to stop fighting or someone else gets the Nobel Prize. Eventually, the other 2 head out and meet Kripke, who pretends to be a friend of them prior to saying he's hating Pemperton and that he cheats in his work. Sheldon And Amy debate with their friends should they get him fired. Howard And Penny don't think so, while Leonard and Bernadette do. Sheldon And Amy are reluctant to expose him and eventually gain evidence from Leonard, which he got from Kripke. They give Pemperton the thesis to win on their own terms rather than tearing him down. However, this leads Campbell to turn on him and they fight. Campbell Gets Pemperton fired and plans to join Sheldon and Amy. However, they reject him and Sheldon wonders what Linda saw in the other 2 guys.
Leonard's mother comes over, paying less focus to Sheldon and more focus to Leonard than usual, leading Sheldon to think she's mad at him. When Sheldon's scrolling through his texts, finding Beverly hasn't responded, Leonard comes over in fury that his mother was just using him, relieving Sheldon, who doesn't provide comfort to a frustrated Leonard. Leonard eventually gives up and decides to make peace with his mother. (The Maternal Conclusion)
Sheldon sings about the half life of radium while waiting for the call that he and Amy won the Nobel prize. Eventually, Sheldon gets a call, though the call's just a prank from Barry Kripke. Sheldon's convinced, despite the obviousness. The next phone call's Howard and Bernadette checking to see if they won. When the call that they won finally comes, Sheldon thinks he's dreaming and Leonard slaps him and the two couples cheer over Sheldon and Amy's victory. Sheldon gets frequent congrats, though all the people he's seeing makes him feel overwhelmed, leading Amy to feel emotionally distressed. Sheldon doesn't like Amy's new haircut and disrespects her, to which Leonard calls him out. Sheldon then sees the elevator's finally gotten fixing post years of not operating and is startled that Penny got down to the lobby faster than him. They go out drinking and Penny slowly gets Sheldon to accept change while they see Howard and Bernadette on the news. Penny gets pregnant, which is revealed in the last episode. (The Change Constant)
Sheldon fixes the DNA model which Sheldon made as a genetic code for an advanced human race in his old apartment that Leonard broke with Leonard, who comments they had a very pleasurable 139.5 hours, which is a subtle reference to the number of Big Bang Theory episodes. Sheldon and Amy hold a discussion on rules of communication in Sweden and head to use The Elevator, which has too much luggage for the seven friends to fit with in. Leonard has an idea, though isn't too thrilled with Sheldon calling him a valuable part of his entourage as a result. Sheldon winning the Nobel prize leads him to start treating his friends with disrespect, evidenced by him dismissing Penny's pregnancy as something he can't catch and calling Howard an idiot in front of Leonard, who's mad at his selfishness and unkind treatment of him and the rest of the group. The three consider leaving when Sheldon dismisses Howard's meltdown and only focuses on his own success and big day. Sheldon hypocritically calls his friends selfish for wanting to leave, which leads Amy to snap at him for mistreating his friends. Sheldon opens his eyes and gives them the respect they've deserved for many years from him, moving Penny to tears. The series ends with them having dinner with all their friends other than Stuart, Bert and Denise, and Sheldon and Amy wearing their Nobel prize, all while the acoustic version of the theme song plays.
=== Young Sheldon ===
==== Season 1 ====
Sheldon starts high school at the age of 9. During dinner with his family, Sheldon shows his loyalty to his mom by accepting her wish to go to church with her. Missy's much more unhappy with said wish and engages in a food fight with Georgie. Sheldon's intellect leads to Georgie getting frustrated and having a dispute with their father. (Pilot (Young Sheldon))
==== Season 2 ====
Sheldon starts taking college classes every Friday from his pen pal, John Sturgis.
While Sheldon comes to college class like any other Friday, he sees another young prodigy whom is younger than him, Paige Swanson, Dr. Sturgis thought it was a nice surprise but Sheldon hates it while Paige loves it, Dr. Sturgis calls it a 50/50 success rate. (A Rival Prodigy and Sir Isaac Neutron)
Sheldon puts up a machine for the Swedish radio, he invites everyone in high school to his garage to listen to the Nobel prize, but no one comes, not even Tam, and due to Dr. Sturgis having an episode, can't come too, Sheldon sits in the garage while the radio announces the winners, Sheldon cries while Adult Sheldon narrates that "A primary feature of quarks is that they're always bonded together, but in that moment, i felt like a neutrino, destined to be alone forever", it cuts to an 8 year-old Leonard (listening to the radio aswell), a 4 year-old Penny (sprawled out sleeping), a 9 year-old Raj (studying), a 9 year-old Howard (playing games while his mother yells at him to go to sleep), a 5 year-old Bernadette (sleeping with her pageant trophies next to her bed), and an 11 year-old Amy (reading Little House on the Prairie in bed), it then cuts back to Sheldon while Adult Sheldon narrates that thankfully, he was wrong. (A Swedish Science Thing and the Equation for Toast)
==== Season 3 ====
Sheldon learns about deep emotions when Paige gets emotional about her parents divorce, he finds a new way of comforting someone by offering them a hot beverage, this becomes a tradition and is often used in The Big Bang Theory. (Body Glitter and a Mall Safety Kit)
==== Season 4 ====
Sheldon finally graduates high school, but is worried about not being ready, but with Mary comforting him, he is now ready for any challenges college can give him. (Graduation)
==== Season 5 ====
Georgie's pregnancy news finally reach to the family, but Sheldon doesn't care about it but he makes a new nickname for the unmarried mother, nibling.
==== Season 6 ====
Sheldon is worried about grad school and tries to persuade the college into making him join one, but, Dr. Sturgis pulls some strings and is able to get him into a grad school in Heidelberg, Germany, and with Dr. Linkletter and Pastor Jeff's funds, he's set to go to Germany.
Sheldon and Mary go to Germany for his grad school, but, a tornado comes along and destroys Meemaw's house, the news still haven't been sent to Mary and Sheldon. ( A Tornado, a 10-Hour Flight and a Darn Fine Ring)
==== Season 7 ====
After Mary and Sheldon got the news, Mary immediately plans a trip to go home. Sheldon tries to rebel but to no avail, however, after coming home from his former college, he sees George in bed with another woman (whom is Mary roleplaying). Since that day, Sheldon never spoke of it to his father and has since then added three more knocks for people to have time to put their pants on. (A Wiener Schnitzel and Underwear in a Tree)
Sheldon's father had died due to a heart attack and the family's grieving in varying ways. Sheldon's way of grieving is thinking of the different ways he could've said goodbye to his father, but it leads to Sheldon not speaking even in his father's funeral, which, he ultimately regrets. The episode ends with adult Sheldon mentioning he loves and will forever miss his father. (Funeral)
Sheldon And Amy make their 1st appearances as adults since The Big Bang Theory series finale. Amy Tells Sheldon to get an ice hockey jersey on and take a shower for their son Leonard's hockey game in an hour. Sheldon says he's working on his memoir and disapproves of said sport. In his youth, the chaos continues regarding Sheldon's dad's death and Mary asks her younger kids to get baptized, which they're reluctant to do. Meemaw begs the kids to get baptized, cause Mary's in so much pain and they agree to baptism. At the church, Pastor Jeff sets Missy off and she backs out of the deal. Sheldon's not happy to get baptized, though does so for Mary and Meemaw. Amy's surprised Sheldon got baptized and Sheldon reveals he got an ear infection, which was worth the price for Mary. Adult Sheldon goes to his son's hockey game in a jersey and he says Penny never should've gotten to babysit their kids upon Amy mentioning her daughter wants to take acting classes. Sheldon Wishes Missy farewell prior to heading to Caltech. (Memoir)
== Characterization ==
Aside from his characteristic idiosyncrasies, and unpragmatic obsessions Sheldon believes humans are illogical and attempts to be logical himself. [Even though, in reality, he's actually significantly more illogical than most people in so many ways (i.e.; fear of change, fear of birds, using his smarts to make others feel dumb, being immature etc.)] He frequently states that he possesses an eidetic memory although the correct term for this type of recall is hyperthymesia (highly superior autobiographical memory) He also states that he has an IQ of 187, though he claims his IQ cannot be accurately measured by normal tests (further confirming his egotism). Sheldon has a generally excessively extensive knowledge of most philosophical principles of certain topics of interest, as shown, for example, by his comments about various details of anecdotal knowledge (for instance, about the introduction of the fork into Thailand). He can remember everything he's exposed to. It was also revealed in "The Sales Call Sublimation" that Sheldon, possibly, has synesthesia. He told Raj that he automatically sees prime numbers as red and that twin primes appear pink and smell like gasoline. These are characteristics of people with synesthesia.
Sheldon also has qualities associated with being a prodigy, such as an inflated ego, social ineptitude, and an inability to relate emotionally with other people. Despite his intelligence, he has a distinct lack of emotional maturity and is often baffled by even the most common social interactions. He not only fails to understand the simplest sarcastic jokes made by his friends but also regards their sadness over problems with blatant confusion.
Eventually he has begun to understand the concept of sarcasm, attempting unsuccessfully to employ it himself towards Penny in the second season, and successfully employing it towards his other friends in the third season. He appears to have a complete disinterest in romantic relationships, and his eccentricities, direct remarks and demanding nature put him at odds with his own friends and especially Penny. For a few years he also showed a disinterest in being romantic with Amy.
Up until "The Empathy Optimization", Sheldon never seemed to have any sense of remorse or guilt. Perfect examples of this include when he ratted out Leonard, Raj and Howard for inappropriate sexual behavior to Human Resources, just because he thought he did nothing wrong (when, in reality, he talked to his assistant about sexually transmitted diseases) and when he puts down Amy by not treating her accomplishments like they were a big deal.
According to Sheldon's Meemaw, it's strongly implied that Sheldon takes after his grandfather, Pop-pop, who was known for being "a stubborn, egotistical man". When the group find an actual prop of the One Ring from The Lord of the Rings Sheldon immediately snatches it off Howard, bluntly declaring "Mine!" and when people protest to this, he claims "I don't understand why, in this group, I never get my way!", completely oblivious to the fact that he always gets his way. When he doesn't get the Ring, he constantly tries to retrieve it, to the point of invading his own friends' privacy and boundaries and effectively stealing it off them (e.g.; he tried to steal it off Penny while she was sleeping, only resulting in her reflexively punching him and breaking his nose and later pickpocketing Leonard while he was relieving himself in the men's room). This particular example shows that his great love for a fictional movie or rights cause him to be extremely obsessed with things that don't really matter in the context of the real world. In conclusion, it can be axiomatically ascertained that Sheldon will try to achieve, retrieve or maintain anything if it meant that he would seem (fictionally or genuinely) superior to "everyone" else.
Sheldon adheres to The Roommate Agreement constantly when things don't go his way and interestingly, Sheldon's styled the roommate agreement so that everything goes his way. Sheldon also officiates in said agreement that he settles all ties, increasing the likelihood that he gets what he wants. That being said, when a clause of the Roommate Agreement applies to him to not do something, he will treat it like it's ridiculous - in the process, hypocritically violating the agreement despite constantly chiding Leonard when he apparently violates it. At one point, when Leonard headed a project for the group, Sheldon labelled him as simply the founder, while he was chief or head of absolutely everything else, making him in charge. He also tried to make the project named after himself, even trying to get by naming the project with his name spelt backwards. Sheldon is revealed by Priya to have repeatedly violated the roommate agreement, and the several demonstrations of this cause deep discomfort and even despair in Sheldon, who becomes vengeful and deliberately damages Leonard and Priya's relationship through blackmail afterwards.
Sheldon does not see fault in absolutely anything he does in his life, to such an extent that he doesn't think that, when he commits a serious crime, he is doing anything wrong. He, at one point, insulted a judge while in court, simply because of his belief that his job and status was superior to the judge's, which landed him in jail for his trouble. Sheldon also stalked President Siebert just to get a simple answer out of him, to the point of following him to his home and then calling him anonymously. Sheldon is willing to do anything to get what he wants even if it's against the law. Prime example is when he deliberately puts all of Penny's clothes on the telephone wires without acknowledging, or even probably noticing. When he finds out he's wrong, he just replies, "Oh!" and doesn't apologize.
He sees it as his absolute right to interfere with something that has nothing to do with his business, and alter it so that it benefits or pleases him, shown at one point when he interfered with Leonard's dating another woman despite it not concerning him at all. Another example is when Penny, after an argument with Leonard which upsets Sheldon, says that "this really isn't about you", his only (strained) response - after a very long pause - is "I don't follow", showing that he doesn't understand why he cannot be priority one in situations that has nothing to do with him. Sheldon also doesn't realize at all that he's an immense burden to everyone around him due to his controlling, condescending, and demoralizing behavior - he rather sees himself as a true privilege to his friends simply out of egomania.
Sheldon is openly pompous and condescending towards people like Howard, treating him like a simpleton - to say the least - constantly. His incredible sense of pomposity is so widespread that he immediately places himself in a position of absolute power, credit, benefit, or authority in whatever project, ambition, or situation which is discussed within earshot of him. He will also meet every single opposition to his authority with immense melodrama - he describes Leonard's control of one notable project as 'Leonard's reign of tyranny', despite being a dictator himself. He's also completely taken off guard when he is excluded from the project, because he's absolutely incapable of seeing anything he's done as a bad thing.
Sheldon can be conceited as he pictures himself as either/or a mentor, teacher, father-figure, sensei, commander, superior and director simply out of intense self-delusion. He does not do any amount of personal labor if he could avoid it, shown by how he is seen with Howard and Raj both carrying huge workloads of Christmas presents, whilst he is only carrying a small cylindrical present in one hand and eating an ice cream cone with the other. He appears completely indifferent, if not apathetic, to the fact that they are on the edge of collapsing from exhaustion and could be crushed under the weight. Another supreme example is when he realizes that Amy is going to work at the same university as he is, and says "You can't work where I work", thinking that he has complete jurisdiction over where she works.
Another key example of Sheldon's selfishness is when he's ill. Sheldon demands that everyone else take care of him, even if they're occupied with other tasks or could be hurt or ill themselves due to never having been ill alone before. He also believes that being ill motivates him to speak to others as he pleases, shown during "The Empathy Optimization". He did not realize how rude he was until Leonard made him remember. 
Though not confirmed, Sheldon appears to have extreme megalomaniacal tendencies. When he was a child, the kind of pet he wanted would be one that was capable of killing at telepathic command. He also, at several points in his childhood, tried to build devices and technologies that would enable him to kill or avenge himself on people who had done him wrong. At several points in his life, he fantasizes about "rising to power", gaining a planet that he can rule with an iron fist, even declaring that he will, one day, have a robot army at his disposal. In addition to this, Sheldon constantly brags that he will, one day, gain a Nobel Prize and suggests to several people that their contributions to his life will earn them a mention in his memoirs (entitled "You're welcome, mankind"). He also sees himself as a world-renowned physicist with an unparalleled understanding of the universe and that he's on the precipice of advancing mankind's understanding of the universe, ignoring the fact that there are some aspects of even science that he has some lack of understanding of, and he is notoriously able to make scientific mistakes - he was rendered absolutely speechless by an equation in a physics bowl which he didn't know the answer to, and was so angry that he couldn't figure it out that he denied the correct answer when it was provided. What this means generally is that he believes that mankind owes him big time, and has done so his entire life.
Sheldon's opinion of his own profession is overly ego-oriented, to the point where, if he sees any occupation of someone else's that's unrelated to his, he tacitly and implicitly admonishes them and boasts about his own. This is exemplified by his extremely low opinions of Howard's profession as an engineer (he constantly scorns Howard's intellect based on him not having a Ph.D. and the fact that he's an engineer), his belief that geology is "the Kardashians of science" and his discredited opinions of biology as a low point on the scientific ladder simply on the basis that it is, in his own words, "all about disgusting, squishy things". However, despite scorning engineering as unimportant, he is shown to be somewhat extremely knowledgeable in the subject himself in terms of general knowledge (certainly not field work) and therefore only condescends the subject because he finds the information and premise "inferior" to that of physics. Sheldon has remarked that it is his dream to be an astronaut, and that he was secretly stunned at Howard being chosen to go into space, stating in his own words that it showed him "they'd just send 'anyone' up there".
Sheldon's expression of his more advanced intelligence has gotten him fired from his job, and even Leonard is surprised to learn that Sheldon is conceited enough to believe that Isaac Newton is intellectually inferior to himself. Sheldon hates it when someone stops him when he is trying to explain something. If he is, a violent tic starts on his face until he can complete what he wants to say, as in "The Friendship Algorithm" when he is prevented from explaining why tapioca pudding is a "jiggling bowl of potential death". He cannot and will not drive, and thus someone must always drive him, unless in an extreme circumstance (like when he drives Penny to the emergency room in "The Adhesive Duck Deficiency".)
Sheldon has done some questionable things, such as when he discovered that Penny's apartment was messy, he sneaks in during the night and cleans it up because he can't stand being in the same hallway with something so disastrous. He refuses to sit anywhere other than his designated spot on the couch and follows set routines. A running gag of the show is that, when he knocks on Penny's door, he has to say Penny's name every three knocks (he does this thrice every time). It was never specified by the series creator why Sheldon does those things.
Sheldon occasionally uses slang (in a very unnatural fashion), and follows jokes with his catchphrase "Bazinga!" He is not entirely sure how to hug someone, and he avoids human contact whenever possible. Despite his ego-centrism, Sheldon appears to be somewhat aware of his social ineptitude, particularly his lack of understanding of sarcasm. He mentioned that he keeps a record of his daily conversations after Penny snapped at him and Leonard asked him why, to which he suggested that Leonard check his conversation records "to see if I messed up anywhere." Sheldon is also a difficult person to work with and generally displays apathy to the world around him. In "The Toast Derivation", Sheldon was revealed to have criticized Bill Gates for focusing on his charity work rather than Windows Vista, a remark that earned him a punch in the face.
Sheldon also possesses some understanding of other religions such as Hinduism and corrects Rajesh when he says cows are gods, when they are actually like gods, and was also knowledgeable about other Hindu beliefs. However, despite being raised in an extremely religious household, Sheldon possesses no faith in Christianity. Even after moving back to Texas, he planned to teach the religious types evolution and only moved back to Pasadena when his mother calls evolution opinion. Sheldon deems karma as "nonsense" and was left baffled when Rajesh deescribed it as Newtonian. Sheldon is extremely germaphobic and is extreme in his methods to avoid catching an illness, such as sterilizing his mouth with whiskey after sipping from Leonard's glass. Sheldon does his best to avoid any human contact; however, as the series continues he became more (albeit only slightly) affectionate person, such as when he hugged Leonard after he returned from Professor Proton's funeral and kissed Amy on board a locomotive. He does not mind Amy touching as their relationship progresses.
Sheldon does, on rare occasions, show interest in relationships, which was most prominently seen with Amy Farrah Fowler. However, he does not express it directly; instead, he develops strange behavior patterns, such as buying cats, refusing to open discussion on the matter. Despite this, however, Sheldon remains completely clueless to the sexual innuendos which were present during his and Amy's anniversary when she became intoxicated, causing her to unbutton her blouse and asking that they skip to dessert, for Sheldon to reply "I just had cobbler." This was also evident when their upstairs neighbor "hooked up" with the producer of CSI and, while the two are having intercourse, he mistakes it for her jumping up and down on the bed. However, there's one situation where he may have understood an innuendo. When Raj, Leonard, Howard, and Sheldon were competing over The One Ring and Penny appears with "a bag from Victoria's Secret", Sheldon and the rest all look at Leonard. He either understood what Penny meant or was looking because everyone else was. Eventually, he does have coitus with Amy but it's only cause that's what she'd want for her birthday. Afterwards, he admits that he enjoyed more than he thought he would.
==Traits Perceived by Other Characters as Annoying==
Due to his eccentric behavior and arrogance, Sheldon isn't well-liked by many people. Due to his belief that he's intellectually "superior", he's not ashamed to insult his own friends, like Leonard, whose work Sheldon deems derivative and who never appreciated his overbearing mother; Howard, who's merely an engineer and not a real scientist, and also doesn't possess a doctorate (despite the fact that engineering has more practical real-world applications, as well as more related jobs, than theoretical physics does, a fact that Sheldon doesn't take into account); and Penny, who Sheldon considers (and in some ways, is) the polar opposite of an intellectual. He often mocks her for having once dropped out of a community college. In "The Thespian Catalyst", Sheldon makes a speech to a class of bored and disinterested grad students, reminding them that they will never be as smart as he is. Teaching is something else that Sheldon fails at having no social skills.
Sheldon's obsession with routine constantly causes friction with him and his friends. In "The Dumpling Paradox", he has an issue with Penny sleeping on the couch, because he wants to watch Doctor Who and Penny is sleeping in his spot. Leonard offers some alternatives, but Sheldon refuses to accept them, because they're not part of his routine. In the same episode, he states that he, Leonard, and Raj can't order Chinese food without Howard. "Basic math simply won't allow it", as Sheldon puts it. Sheldon's routine is even written for everyone to view, except for 2:45 to 3:05 in the afternoons, where he spends some recreational time in a storage room in the Caltech basement. Even his recreational time is planned and he spends it doing the same thing—playing keepie uppie with a hacky sack.
Sheldon's also been shown to have issues with closure. An example of this is when he has a near meltdown when he learned that one of his favorite sci-fi shows, Alphas, had been cancelled after a cliffhanger. Amy tries to break him out of it using several exercises. Sheldon seems to overcome his closure issues, but after Amy leaves, he finishes all the exercises.
Also, due to his lack of emotion and his inability to understand sarcasm, Sheldon never seems to realize when he's in trouble. When other people get mad at him, he blames them (their inability to "properly" understand the situation or the fact that they can't control their emotions). In "The Einstein Approximation", Sheldon tries to get a menial job. The woman at the employment office doesn't understand his behavior, and when he tells her he works as a physicist at Caltech, she thinks he's crazy and calls security. Sheldon isn't fazed by this, because in his mind, he's done nothing wrong, and he casually waits for her to return so they can finish.
Sheldon has also been shown to be very impatient. This would come back to haunt him, as he'd hound Amy after she told him she needed space. Unable to understand this, he showed up after 11 hours, thinking that was enough time. He also continuously asked Amy whether or not they'd actually broken up without giving her time to think about it. He ultimately went too far, causing her to officially break up with him.
Sheldon can be selfish, evidenced when he ditched Raj while they were underground while only thinking of his own safety. He also says that the roommate agreement was made to get the right way and that the fact that "his way" is the right way's a happy coincidence. In the series finale, his victory of the Nobel Prize leads him to selfishly dismiss Howard's concerns for his kids and Howard says he and Bernadette were going home as a result, with Leonard and Penny joining cause of him dismissing Penny's pregnancy, only changing when Amy called him out on how he was treating their friends.
==Childlike Qualities==
Sheldon also possesses many childlike qualities. For example, though unaware of it, he's extremely stubborn. Examples of this include naming the The Physics Bowl Quiz for Caltech, deciding to go to San Francisco by train instead of flying (due to his love of trains), his needing of his mother (or Penny) to care for him when he is sick, which involves singing "Soft Kitty", having his Homemade Soup made for him, and rubbing Vicks VapoRub on his chest. He cannot stand to be interrupted, concede when he doesn't know something, or hear people bicker or argue, which results in him crinkling his lips with intense frustration when any of these events occur. Sheldon hasn't attempted to obtain a driver's license (though he does possess a learner's permit) and needs his friends to drive him everywhere; he refuses to take the bus. He attempts to learn to drive on a simulator, but fails instantly. Sheldon's excuse for this is that he is "too evolved" to perform "plebeian tasks" such as driving. Amy eventually teaches him to drive which he does returning from the desert with Howard. He drives so fast that the police stops him and he just gives his license to the policeman permanently.
In Season 5's "The Pulled Groin Extrapolation", Amy asked Leonard to attend a wedding with her. Leonard asked why she did not ask Sheldon to go instead. Amy answered that Sheldon behaved like a child the last time so he is out. After Amy left, Sheldon said in a sing-song tone to Leonard; "Ha-ha, you have to go to a wedding!" as he was unwrapping his newly bought toy train set, further emphasizing his childlike qualities (also revealing he didn't want to go anyway).
He has also shown some slightly childish fear. In the Season 2 Episode, "The Euclid Alternative", Sheldon mutters something that shows that he has a night-light ("Maybe I could keep my sheets if I turn out the night-light").
However most of these problems can be traced back to his root personality fault of stubbornness.
==Interests==
Like his friends, he is scientifically inclined, and is fond of Comic Books, costumes, video games, flags and science fiction, specifically Battlestar Galactica, Doctor Who, the Stargate series, Star Trek, Star Wars, and Firefly, although he strongly dislikes Babylon 5 because he thinks it "lacks scientific integrity" and is "derivative". He has claimed to be an honorary graduate of Starfleet Academy, and is an avid fan of Science Officer Spock. Other favorite characters of his are Batman, Spider-Man, The Hulk, The Flash, Superman, and Frodo Baggins.
He likes playing Halo every Wednesday and paintball on the weekend with his friends. He can also play the piano and theremin, and seems to be a very good Tuvan throat singer, but would be better if not for a part in the Roommate Agreement denying him practice.
Sheldon also loves making agreements (Roommate Agreement, Relationship Agreement...), one of his dream was even to become a notary public, a dream that became true, as said in season 5. (« The Wiggly Finger Catalyst ») He had a former and very short-lived interest in acting after he lost a science fair.
==Physical Appearance ==
Sheldon is a tall, lean, yet well-built man, originally in his late twenties, but he's in his late thirties by series end. He is 6' 1" (1.85 m) with brown hair and blue eyes. His wardrobe consists of vintage T-shirts (which he always wears over a long-sleeve shirt) adorned with references to superheroes, quantum physics, Sci-Fi television shows, and robots. Sheldon often expresses his mood through his choice of attire; especially his t-shirts. He's got a collection SO large in fact, that it has its own page on the Wiki under Sheldon's Wardrobe. He also owns a dark blue plaid suit which he wears for lecturing and other formal occasions. Later he had a less loud suit.
He also appears to enjoy Reddit, as he has been seen with a Snoo (the Reddit mascot) shirt. He usually wears a long sleeve shirt underneath it along with plaid pants. Sheldon is tall and thin (setting him apart from his shorter colleagues), with Penny, and later Leonard, saying he looks like a giant praying mantis.
In Season 1 of Young Sheldon, Sheldon is a rather tall, skinny, adorable 9 year old kid (10 later on). He is about 4' 5" (1.35 m) and his hair is slightly brighter than in The Big Bang Theory. In fact, in The Big Bang Theory, while he is an adult, his fashion is more childlike; however, in Young Sheldon, while he is a kid, his fashion is more adult-like.
==Drugs and Alcohol==
With few exceptions, Sheldon refuses all drugs, including alcohol and caffeine, as a promise to his mother (though it's suggested in "The Codpiece Topology" that he drinks Red Bull, which contains caffeine). In addition, when Penny mixed alcohol into his drink making it "slutty", he began to play the piano and sing "To Life" from the musical Fiddler on the Roof in front of an audience. A small amount of coffee made him extremely hyperactive, but unproductive in another episode. Taking Valium also affected his behavior. Probably the most infamous time of him being drunk was when he had to give a speech in "The Pants Alternative" and he acted like a comedian due to the abundance of wine he drank to calm his nerves. The scene was uploaded on YouTube where it is revealed Sheldon also took off his pants and mooned the audience. Howard once drugged him with his mother's sleep medication to get him to stop talking, but was unsuccessful. He exposed Penny's secret about her college career to Leonard.
While it's argued that Sheldon drank beer in the Pilot, it's actually an orange soda (clearly seen when Leonard holds up his bottle in the hallway).
He does enjoy a Mountain Dew in "The Vengeance Formulation", one of the more caffeinated sodas, even calling it "refreshing". He also likes "diet virgin Cuba Libres", which is essentially a Diet Coke with a slice of lime. It appears that he can drink caffeinated beverages to a certain point, but not to the extent of coffee, which he considers a drug.
In "The Habitation Configuration" Penny serves him numerous glasses of Long Island Iced Tea, which he enjoys; however, he's unaware of the fact it's alcoholic (and not actually tea as he genuinely believes) and Penny makes no move to correct his assumption. This drastically affects his behavior to the point where he attempts to "beat" an apology out of Wil Wheaton.
In "The Thanksgiving Decoupling" he drinks beer with Bernadette's father since his own father died before they could do so. As a result, he became drunk and did numerous things, like burping pi, or as much as he could without throwing up, making fun of Howard's mother and her "bathroom clowns" by saying you could only fit one of her in a car, and insulting Howard, calling him the "clown that came out of her". After apologizing for his behavior, he sent Amy to get him and Mike beers and slapped her on the butt, much to her pleasure. Later, he threw up on the clowns in the bathroom.
In "The Dependence Transcendence", the Flash appears to a sleeping Sheldon and tells him that all superheroes use energy drinks and take performance-enhancing chemicals. The Hulk uses steroids and Batman stalks the night looking for fights because he drinks scotch. He gives Sheldon his first energy drink free because he invested his money in Marvel Comics, the rival comic book company. He goes hyper while working on their gyroscope miniaturization project and then drives everyone crazy thinking that he was addicted to energy drinks.
== Softer Side==
Despite his strange behavior, Sheldon has, at times, demonstrated a much softer side to himself. He does seem to be quite a heartwarming character; however, these moments are rather rare, and usually only reserved for those closest to him, such as his mother, Meemaw, Amy, and his friends.
Although his friendship with Leonard is usually strained because of Sheldon's quirky behavior and weird habits, Sheldon has called Leonard "his little buddy", or something of the sort on multiple occasions. He also shows an obvious unease whenever his friendship with Leonard is threatened.
Sheldon's also shown friendly acts of caring towards Penny. In one instance, when Penny was low on money, Sheldon let her borrow a large amount of his savings, but while she worried about paying it back, he was entirely unconcerned as to when he got it back. Sheldon's willingness to lend money to others was later described by Leonard as "one of the few idiosyncrasies that doesn't make you want to, you know, kill him". Also, after Penny let him stay at her place when he locked himself out of his apartment, Sheldon sincerely thanked her for it.
When Penny fell and dislocated her shoulder, Sheldon spent the entire night taking care of her, including driving her to the hospital despite the fact that he does not know how to drive. He finished the night by helping her into bed and singing "Soft Kitty" to her after she asked him to. He also hugged Penny again when she said she would talk to Leonard about having him take Sheldon to Switzerland rather than her. This prompted him to sincerely thank her and hug her. When Howard's mother died, Howard fell into a depression as Sheldon told him he understood his pain as he lost his own father and though he didn't have friends at the time to help, Howard did causing the latter to smile as these comforting words. This was one of Sheldon's kindest moments as all his friends expected him to be rude especially Leonard and Penny who were moved by his words.
With the exception of his family, Penny, Wil Wheaton, Amy and Leonard are the only people Sheldon have hugged. With Amy, he specifically cuddled with her in the episode "The Isolation Permutation", after a discussion to console a weepy Amy who was craving human intimacy and physical contact. After turning down Amy's previous proposals of getting into bed together and French-kissing, Sheldon agreed with her final offer to cuddle, though he got upset over it later, by yelling at Leonard and Howard to keep Penny and Bernadette in line and have them apologize to Amy since consoling Amy had caused him to miss the time he had designated to solve Space-time Geometry in Higher Spin Gravity and building his Lego Death Star. This particular event of him cuddling with Amy is a huge development of his personality since he is not shown to have much empathy or sympathy for others. Amy is his one big exception.
His caring attitude towards Amy is also exemplified when he buys her a diamond tiara as a form of apology after having a fight regarding the importance of Amy's accomplishment when her research made the cover of a noteworthy science magazine. In another instance, Sheldon acted disrespectfully in Amy's laboratory when he was taking his required vacation time. The next day, however, he returns and after a few attempts, meekly apologizes to Amy, showing a vulnerable side of him that isn't usually seen considering his egotistical attitude. Perhaps the greatest leap forward in Sheldon's willingness to show his softer, more emotional side to Amy is when he voluntarily, without any prior prompt from Amy, held Amy's hand while Howard's Soyuz Rocket was being launched into space. Amy was shocked at this, since Sheldon had acted confused and oblivious when she had tried holding his hand in "The Alien Parasite Hypothesis". In season 6, he objects to Amy making him hold hands as he considers it unhygienic.
He also takes care of her when she was sick even though he first starts to leave and then thinks better of himself.
After 8 seasons, he finally enjoys making out with Amy after being disturbed by it. On Amy's birthday, he decided to have coitus with her in season 9 to show her how much he cared for her. He later admitted that he gets turned on by interaction with her in season 10. Shamy seems to get turned on discussing or arguing about science.
A long time ago, he always had been rude and offended a lot of people. Mostly he never apologizes for being a jerk. In later seasons, he started maturing and starts apologizing to people every time he is being a jerk or being rude when somebody tells him. In the series finale, he was going to make a self-centered speech when he won the Nobel Prize and rub it in the fact that he won in people's face. Instead he thanked his friends and his family for making him a better person and helping him and tolerating him all the way up to winning the Nobel prize alongside apologizing for his poor treatment of his friends earlier.
==Religion==
In contrast to his profoundly religious mother and devout evangelistic Baptist upbringing, Sheldon has no interest in religion - he tends to ignore or express dislike for religious celebrations such as Christmas, and wastes no time in bringing up the Pagan origins to each festival. Additionally, his scientific beliefs often come into conflict with the spiritual beliefs of his mother, Mary. Nevertheless, he has an agreement with his mother to attend church once a year, and once exclaims "Thank you, Jesus!" upon getting a strike in a bowling match against Wil Wheaton (his arch-enemy). His attitude towards God has been hinted at being of an Agnostic nature, when in the episode "The Zarnecki Incursion" he says "Why hast thou forsaken me deity whose existence I doubt..." Raj stated that one of the instance where Sheldon got food poisoning and he was "praying to the god he doesn't believe in to end it quickly". When he sees his mother having sex, he is very concerned about the hypocrisy shown by his mother having relations outside of marriage yet expounding the Bible to him throughout his childhood, even going as far to declare "don't turn to him, he's mad with you" when his mother uttered "oh dear Lord" during the conversation. He possesses knowledge of other religions and denominations, such as Hinduism, Judaism, Catholicism (a denomination of Christianity)
== Legal Issues==
Sheldon also appears to have problems understanding the law at times. Sometimes, his expertise of lock-picking gets him in trouble. He is shown to drop objects out his window into traffic without any regard, in addition to breaking into buildings. He has also been seen going into various places, such as a kid's ball pit, and even began working at the Cheesecake Factory without being granted permission. He has expertise with picking locks and disarming alarm systems. Furthermore, the Department of Homeland Security notifies his mother when he acts contrary to federal law. As he states later, "Apparently, you can't hack into a top-secret government supercomputer and then try to buy uranium without the Department of Homeland Security tattling to your mother." This implies that Homeland Security is familiar with him, as instead of arresting and questioning him, they simply informed his mother and let her deal with him. He also states that he has been arrested for jaywalking when he said to a police officer "You just saw me jaywalk, aren't you going to arrest me. Maybe I should arrest you for impersonating a police officer". Another notable trouble with the law involves Sheldon going to court for running a red light when taking Penny to the emergency room. This resulted in Sheldon being found guilty and forced to pay the cashier, only for him to insult the judge and being thrown in jail simply because he refused to apologize for his comments. In addition to apologizing to the traffic court judge and paying the fine, Sheldon was forced to accept three points on his non-existent driver's license. Despite these legal mistakes, Sheldon is not above turning his friends and family in for breaking the law.
==Traits==
Sheldon has qualities include social ineptitude and many more traits which make him the most eccentric and bizarre of the characters in the show. The writers did not want to identify his condition and have people disagree with his future actions as not consistent with the medical condition. Many of these traits are the reasons why Leonard finds him hard to live with and his friends find him so hard to be around. These include:
*Obsessive–compulsive disorder: Sheldon exhibits a strict adherence to routine, such as doing specific recreational activities on specific days of the week, going to the bathroom on a specific time every morning, eating specific food items on specific days, being unable to reconcile changes to food orders, doing laundry on a specific day and time (every Saturday night at 8:15), knocking on the door a certain number of times while repeating the name of the person he is seeking with a particular frequency ("[knock knock knock] Penny [knock knock knock] Penny [knock knock knock] Penny" being the most common) or sitting in one spot not allowing any one else to sit there. Amy Farrah Fowler notifies this to Sheldon as a symptom of Obsessive Compulsive Disorder and she finds he is in denial over it. Sheldon labels all home utensils, appliances, etc., including his label maker. He also makes loud noises (or musical notes with a toy xylophone) in every theater before a movie, attempting to locate the "acoustic sweet spot"; however, he can adapt to seats with sub-optimal conditions, such as suitable cushion densities and light dispersion, provided he has the opportunity to test them. Ironically, Sheldon has actually displayed great resilience in cases where his routines and/or living conditions have been severely altered. An example is the expedition to the North Pole; while Leonard, Raj, and Howard all thought it was horrible, he thought it was "a hoot and a half". Another is "The Bozeman Reaction", when he is able to stay awake long after his usual sleep time out of fear that the apartment will be burglarized. He also makes a habit of comparing his petty dilemmas with more serious situations and events, such as:
**Sending "samples from a bag of excrement that had been lit on fire on [his] front porch for fingerprinting and DNA analysis" to the FBI Crime Lab and stupidly expecting a response (after 18 years, he, unsurprisingly, still hasn't heard back yet).
**Calling Pest Control when a bluejay appeared outside his window, and admitting on the phone that he would have called the police if it was actually inside the apartment.
** Calling the FBI when his World of Warcraft account had been hacked, then calling the local police when the former predictably hung up on him.
** Comparing being dragged to the Wolowitz House to being treated like a black slave.
*Narcissistic personality disorder: Though not technically meeting all of the requirements for a formal diagnosis, Sheldon constantly points out his superiority among his friends and belittles everyone at regular intervals. Sheldon does not treat anyone as his equal, and believes that only his ideas are right. Two exceptions are Stephen Hawking and Amy Farrah Fowler. As a result, he does not take the suggestions of others seriously. He also refuses to admit he did anything wrong, often blaming mistakes on trivial reasons and just says "Oh.". Sheldon even admitted he was an egomaniac while drunk once in "The Habitation Configuration", although he quickly took it back. This implies he's at least somewhat aware of how he acts, but normally subconsciously denies it.
*Aphephobia: Sheldon can display symptoms of aphephobia, the fear of human contact. Sheldon admits this in "The Cooper/Kripke Inversion" stating he's been afraid of all forms of physical contact since childhood; however he also reveals he's been purposely trying to overcome it for Amy's sake.
*Mysophobia: He is constantly worried about others touching his food, washes his hands as often as he can, and showers twice daily. Leonard used his concerns for food to mock him in "The Einstein Approximation", as did Raj in "The Engagement Reaction". Penny has stated that he still has not learned to not to insult those who handle his food, to which Amy Farrah Fowler agrees. For example, when Penny touched one of his onion rings and put it back, Sheldon threw out all of the onion rings, saying that she had "contaminated their integrity." He does not seem to do much when Penny implies that she spits on his hamburger at the Cheesecake Factory. When Sheldon was making a video for his future crazy self, he tells himself that he can accept any food that Penny gives him.
*Ornithophobia: Sheldon has had horrible experiences with birds in his past, which has led to ornithophobia (a fear of birds). When Sheldon was a toddler, a hummingbird, which he describes as the vampire of the flower world, dived down into his stroller and tried to get at his apple juice in his Sippy cup. When he was seven, his neighbor's chicken got loose and chased him up the big elm tree in front of his house. When he was twelve, a magpie tried to take his retainer out of his mouth and when he was 16, a parrot in the pet store window called him "fat ass". In Florida he was attacked by a seagull on the beach. This even caused him to fear (and have nightmares of) Sesame Street's Big Bird and put creator Jim Henson on his enemies list. He finally overcame this fear after he was forced to confront a black-throated Magpie-Jay.
*Hypochondriasis: He is extremely terrified about becoming sick. He became worried about Penny infecting him with influenza and subsequently contracted it. Another time, he wanted a full medical examination by Leonard's girlfriend, Dr. Stephanie Barnett, in order to discover the cause of a high-pitched noise in his head. This was later used against him by saying that he had an inflamed larynx and that he needed to stop talking immediately. When Howard's mother is sent to the hospital, Sheldon refuses to go due to exposure to pathogens and germs, until Penny confronts him. Though, he accidentally wanders into a bio-hazard room at the hospital, after fearing the restroom's cleanliness, and endures a two-week quarantine. Sheldon showers twice a day and washes his hands as often as he can. In addition, Sheldon has a red toothbrush that is kept in a Plexiglas® case under a UV lamp.
* Inability to lie: When Sheldon is complicit in a lie; he exhausts all of his efforts in his almost always unsuccessful attempt to make it believable. Similarly, he cannot be entrusted with a secret because he develops nervous tics; however, it is easier for him to lie if he has prior knowledge of the deception or an "ironclad alibi" thought out in advance, as opposed to it being "impromptu dishonesty". Penny taught him a way to lie using sarcasm.
*Intolerance of people in his bedroom: One time, he was distraught when Penny entered his room in the middle of the night. On another occasion, Sheldon hesitantly let Penny in his bedroom to get a key for his desk to retrieve a USB flash drive, constantly reminding her that, far from creating a permanent easement, it was only one-time permission; however, he doesn't seem to mind giving up his room to a guest as in "The Psychic Vortex", he had no problem with letting Martha sleep in his room while he went to do so in Leonard's room instead. Likewise he also gave up his room to Elizabeth in "The Plimpton Stimulation". This probably due to his southern heritage.
*Stage fright: While perfectly comfortable speaking to small groups, Sheldon cannot speak to crowds deemed large enough to trample him (36 adults or 70 children) without having a panic attack or fainting.
*Hemophobia: He has fainted at the sight of his own blood. This might just be part of his over active feelings of self-preservation though, as he didn't seem to have a problem seeing Howard or Leonard's blood.
*Fear of traffic accidents: In "The Adhesive Duck Deficiency," Sheldon laments the irony of possibly dying in a car accident while driving Penny to the hospital. In "The Cruciferous Vegetable Amplification," while Leonard is driving Sheldon's Mobile Virtual Presence Device, he relishes the ability to enjoy being a "passenger" without the threat of a car accident. In "The Euclid Alternative," he refuses to ride a bus due to the lack of seatbelts and told he was forced to leave a bus after attempting to use bungee cords as seat restraints. This likely also stems from his self-preservation. This is also a likely factor to why he has yet to proceed his driving license past a learner's permit.
*Possible sadistic/psychopathic tendencies: Although Sheldon has never actually done anything psychopathic, particularly in the later season, he often implies, and sometimes directly states (always casually) a preference for cruel methods, or even killing. For example, his suggestion to the problem of the elderly being alien to new technology, is to publicly execute a few to give the others some incentive to learn. He also suggested they kill Leonard's old bully when he stayed the night with them, pointing out they had the greatest opportunity to do so. He also mentioned he would like to put, and leave, Amy in a stockade in a public square, for lying to him. On one notable occasion, he even (admittedly half-heartedly) attempted to poison Kripke, when he wouldn't let him have Professor Rothman's office. As Sheldon doesn't lie, and doesn't understand sarcasm, it can be taken he is generally serious.
He also keeps a record of what he considers faux pas "strikes", which he allocates to those who violate his self-imposed conditions. Upon receiving three strikes, Sheldon gives them the choice of apologizing, being "banished" from the apartment for a year, or taking a "class". For many of the aforementioned characteristics, Sheldon's friends often consider him "insane" or "crazy" despite Sheldon's repetition of another catchphrase "I'm not insane/crazy! My mother had me tested." His mother later confirms this to Leonard; the doctor said he was sane, but she regretted not following up with a specialist in Houston.
Despite Sheldon's personality disorders and difficult habits, his friends usually just do what he says because it is easier. In the final episode Sheldon learns that his friends only tolerate him because they know he doesn't realize he is exhibiting these traits on propose. In his final speech he thanks them for their support and apologizes for not being a better friend.
It has also been revealed that Sheldon has a bifurcated uvula, something which he is self-conscious about.
== Sheldon's Spot on the Couch==
 
The most notable feature of Sheldon's obsessive-compulsive disorder is his refusal to sit anywhere other than his designated spot on the far left cushion of the couch in his apartment, which he considers his "single point of consistency in an ever-changing world" and "the singular location in space around which revolves my entire universe", exceeding his love for his mother. He describes his spot on the couch as being his point 0, 0, 0, 0 if his life were a Cartesian coordinate plan. Sheldon regularly reproaches Penny and other people for sitting in his spot. Even disruptions to this location are enough to disturb him. Although he did allow Penny to sit in his spot in the first episode, as well as Howard, for a short time in "The Apology Insufficiency", only 94 seconds later, he reclaims his spot. As well as his designated spot in the apartment, if Sheldon is ever in a different area where he is going to sit down, such as Penny's apartment, he has to choose the best sitting location based on such things as optimal television viewing, lighting, airflow, and cushion density. In "The Werewolf Transformation", when his barber was ill and chaos ruled his life, he didn't object to Penny sitting in his spot. In "The Mommy Observation" Leonard reveals that Sheldon has a very sensitive butt and can tell when someone was sitting in his spot. However, when at the North Pole the furniture in their cabin was arranged like in Apartment 4A with his spot being in the appropriate location.
==Quotes ==
:"Bazinga!"
:—Quote when he makes a joke or a prank.
:"(knock x 3) Penny! (knock x 3) Penny! (knock x 3) Penny!"
:—Quote from various episodes whenever he knocks on the door of Penny's apartment.
:"That's no reason to cry. One cries because one is sad. For example, I cry because others are stupid, and it makes me sad."
:—Quote from "The Gorilla Experiment"
:"On the contrary. I found the Grinch to be a relatable, engaging character, and I was really with him right up to the point that he succumbed to social convention and returned the presents and saved Christmas. What a buzz kill that was!"
:—Quote from "The Maternal Congruence"
:"I'm attempting to view my work as a fleeting peripheral image so as to engage the superior colliculus of my brain."
:—Quote from "The Einstein Approximation"
:"How could somebody possibly think we’re going to blow up the moon? That’s a great question."
:—Quote from "The Lunar Excitation"
:"WHEATON......................................................................................................!"
:—Quote from various episodes, usually after Wheaton messes with him
:"I am not crazy, my mother had me tested."
:—Quote from various episodes, always said after someone calls him crazy.
: "Put it on the back burner. Anyway, it occurs to me, if I ever did perfect a time machine, I’d just go into the past and give it to myself, thus eliminating the need for me to invent it in the first place."
:—Quote from "The Luminous Fish Effect"
: "My mother says when we deceive people for personal gain we make Jesus cry."
:—Quote from "The Classified Materials Turbulence"
:"Leonard, I'm clearly too evolved for driving."
:-Quote from "The Euclid Alternative"
:"Live long and suck it, Zachary Quinto."
:- Quote from "The Recombination Hypothesis"
:"I'm Batman. Shhh."
:-Quote from "The Bad Fish Paradigm"
:"Don't you think if I was wrong I'd know."
: - Quote from "The Jiminy Conjecture"
==Relationships==
===Platonic===
====Leonard Hofstadter====
Sheldon is the best friend of Leonard, as they live together and are accustomed to tolerating each other's quirks ever since Sheldon put out an ad for a roommate with a list of criteria to follow. When Leonard first met Sheldon he had a bunch of rules that Leonard had to follow and a series of questions to answer. Despite Sheldon sometimes making remarks to the contrary, he appreciates Leonard and assures him that his friend will not die alone. He even once told Leonard that he platonically loves him, when Leonard had to face his old high-school bully, Jimmy Speckerman. When Penny asks Leonard why he deals with Sheldon, he explains that Sheldon has actually saved his neck a few times, such as when he stopped him from being incinerated by his own improperly formulated rocket fuel and didn't tell on him to the landlord, the police or the Department of Homeland Security. This incident also lead to the destruction of the elevator, as Sheldon had just enough time to put the explosive contents of the container into the elevator before it exploded. Leonard also, more than all of Sheldon's other friends understands him the most, as viewed in many scenes where when all hopes failed to get Sheldon to participate in something, Leonard will be the last resort to come up with something successful. When Penny and Sheldon had a spat due to Penny sitting in his spot and touching his food and later refused to apologize to him, which resulted her being banished from the apartment, Penny came up with her own set of revenge, including banishing Sheldon from the Cheesecake Factory and messing up with Sheldon's Laundry Night. When things got really ugly between the two, a fed up Leonard secretly gave Penny Sheldon's mother's phone number, telling her it is Sheldon's Kryptonite. The feud ended after that, with Sheldon, clueless to the fact that it was Leonard who helped Penny, told Penny that she played well. Another instance was when Penny tried her hands at opening her own business by selling Penny Blossoms. When they had to stay awake all night to help Penny meet her order, a sleepy Sheldon refused coffee and decided to head to bed instead, leaving the rest to finish up by themselves. A frustrated Penny looked on to Leonard to do something and Leonard did, by saying to Sheldon that without his insight and leadership this entire enterprise will surely fail, which prompted Sheldon to change his mind and drink coffee. In "The Septum Deviation", Sheldon objects to him have elective nasal surgery due to the risks of surgery indicating that he really cares for Leonard despite his condescension. Sheldon and Leonard have co-authored at least two scientific papers together. 
In "The Proton Displacement" (S7E07), Leonard explains why he puts up with Sheldon and takes Sheldon as his friend:
:"Look, I know he can be aggravating, but what you have to remember is that he is not doing it on purpose. It's just how he is. He is also loyal and trustworthy, and we have fun together...You know what, Sheldon is the smartest person that I have ever met. He is a little broken and he needs me. I guess I need him, too."
In "The Space Probe Disintegration", Leonard tells Sheldon that his attitude is why he and Penny are not living together. After a tearful period thinking about them him moving out, Sheldon lets him go one night a week to stay at Penny's. Sheldon still sleeps on her couch that night.
In "The Skywalker Incursion" the guys drive up to George Lucas' Skywalker Ranch headquarters to see if they could get in. They can't so Sheldon rushes the gate, gets caught by being tased and almost gets the two of them arrested. Leonard is mad, but still calls it an adventure.
In "The 2003 Approximation", Leonard finally moves out to live with his wife Penny; however, in the end Penny agrees that they will spend at least half their nights back in Leonard's old room.
In "The Convergence Convergence, Sheldon invites his mother to Penny's wedding re-do without consulting the couple. He still considers himself part of their romantic relationship. Sheldon does not notice the growing affection between Leonard's father Alfred Hofstadter and his mother who bond over their mutual hatred of Beverly Hofstadter, his charm and his respect for other's beliefs. He is very uncomfortable when he can't contact his mother and that she is probably hooking-up with Alfred.
In "The Conjugal Conjecture", Sheldon stands up during Leonard and Penny's vow renewal to tell them how much he loves them even though he often doesn't show it. He is also worried over them becoming step-brothers if their father and mother get married.
In "The Matrimonial Metric", Sheldon and Amy test their friends for positions in their wedding party. The gang gets pissed and no one wants to be in their wedding. Later Leonard tells him that his best man is his own choice and Sheldon choses him.
In "The Bow Tie Asymmetry", Leonard is very happy for his buddy Sheldon when he is about to get married. He is also happy that Sheldon was now legally Amy's problem, but Sheldon says that that is not going to stop him from being his problem. After the wedding ceremony is delayed, Leonard checks up on them and finds Sheldon and Amy inventing super asymmetry which also gets Leonard fascinated and involved. Penny has to come and get the three of them to start the wedding.
In "The Citation Negation", Leonard helps Sheldon with the footnotes in his Super-Asymmetry paper and finds an old untranslated Russian paper that states that Super-Asymmetry is not worth pursuing.
In "The Stockholm Syndrome", Sheldon is still acting superior and due to Amy's tough-love words, Sheldon realizes it and then thanks Leonard and the rest of his friends for tolerating him in his Nobel Prize speech.
====Penny====
Despite Penny not being a smart person nor sharing many of the group's interests, and having almost constant fights with Sheldon in the early episodes, they became best friends. Penny does care for Sheldon during illness or Penny takes him in when he is locked out of his apartment while his friends are in Las Vegas. Sheldon returns the favor as he cares for Penny when she dislocates her shoulder. In all of these instances, the story line ends with one of them singing "Soft Kitty," a song Sheldon's mother used to sing to him when he was sick. On the one hand, Sheldon and Penny spend a lot of time getting on each other's nerves: Sheldon often mentions how uneducated or untidy Penny is, while Penny likes to irritate him by sitting in his spot, messing with food, and they once started a futile war (Penny blocked Sheldon from doing his laundry on his laundry day, and he responded by throwing her clothes and underwear out the window). Also when he asks Penny for something or uses her as an example, he ends up inadvertently insulting her; however, they also efficiently team up, for example to plan Leonard's birthday (Sheldon only participated when Penny blackmailed him into helping) or to develop Penny's "Penny Blossoms" business, singing along to sailors songs to motivate each other. They end up spending a lot of time together as two best friends to help each other and give each other advice (Penny helping to find a suit for Sheldon for an awards ceremony, or seeking Stan Lee's address for him because he couldn't meet him as the other members of the group did; Sheldon teaching Penny physics to help her in her relationship with Leonard). On a few occasions they also appear to share a sort of intimacy that Sheldon doesn't have with anyone else: they both take care of each other when they don't feel well; they stayed together in the flat, cranky and grumpy, as they had both caught the flu after a hug they had exchanged; Sheldon has an immediate, very nervous and alarmed reaction when he hears Penny calling for his help from her flat; they sing together "Soft Kitty" as a round in a kind intimate moment; Sheldon adds an amused "Bazinga" to one of Penny's jokes, to which she replies with a tender "Hmm..." Often when Sheldon seeks advice or help from Penny he begins his request with "you're so good at...." one of her faults and ends up insulting her though she usually lets it pass with a "WTF" expression. Amy has shown jealously of this closeness between the two of them even after she moves in with Sheldon.
Sheldon acknowledges Penny as one of his best friends (along with Leonard and Raj), while he considers that Howard is a "treasured acquaintance," though he has known him a lot longer than Penny. Also, when Penny and Leonard break up, Sheldon still considers Penny a friend and makes dinner plans, which he tries to hide when Howard informs him that it is inappropriate behavior and "bros come before ho's." He actually goes through a lot of trouble (hiding frozen hot dogs in his pants, confronting a huge threatening dog ... ) just to dine with her, though he's already been forced to eat a whole meal with the boys. In the end, Leonard and Penny in a way share custody of Sheldon, taking him to Disneyland and out to buy new shoes.
The interaction between Sheldon and Penny has been praised by critics. James Chamberlain of IGN wrote: "Cuoco and Parsons are great in their own right, but when put together, they truly shine." Matt Roush of TV Guide said that Sheldon and Penny's "scenes and episodes together are usually Big Bang at its best." Todd WanDerVerff of The A.V. Club wrote that they "made such an inspired odd coupling that at times, it seemed as though the entire show were about them" and their chemistry "has some of the rattle and rhythm of the great comedic duos".[73] Chuck Lorre stated that Sheldon and Penny have "become a natural comic pairing" and that they "bounce off each other beautifully."
In "The Intimacy Acceleration", Penny and Sheldon conduct a psychological experiment which should result in the couple instantly falling in love. Sheldon wants to do it because he thinks its poppycock, and Penny does it because she gets to ask Sheldon a lot of personal questions that he has to answer honestly. They admit a lot of truth about themselves like Penny wishes she were as smart as the others and that she uses comedy to cover up insecurities. Finally they stare into each other's eyes for four minutes and decide that they do have a new found intimacy though just as a brother and sister. 
In "The Celebration Experimentation", Sheldon ran into the bathroom after overwhelmed by the birthday party they were throwing him. Penny went into talk to him claiming that it was okay if he wanted to be there. She would probably have tortured him along with his sister and friends at his birthday party when younger, but now that she knows him, he is one of her favorite people. Penny would be happy to spend his party in the bathroom with him. Sheldon doesn't want people think that that is weird. Penny explains that everyone things he is weird, but still loves him and came to his party anyway. Later at the party, Penny makes him hug her and he has upgraded his feeling toward hugs to being mildly irritating.
In "The Viewing Party Combustion", Leonard get tired of the quarterly Roommate Agreement meetings where nothing important is ever discussed. Penny who has signed the latest on as an occupant of the apartment and wants to attend since she gets to lead them in the pledge. Leonard sulks about attending the meeting which makes Penny mad driving her and Sheldon over to her apartment breaking the group into two separate camps. Leonard also points out the weird brother/sister relationship she and Sheldon has which Amy is also jealous of. Penny often takes Sheldon's side due to her sibling feelings for him.
In "The Conjugal Conjecture", Sheldon stands up during Leonard and Penny's vow renewal to tell them how much he loves them even though he often doesn't show it.
In "The Long Distance Dissonance", Penny has to explain to Sheldon that Ramona Nowitzki had a romantic interest in him despite Amy being his girlfriend.
In "The Bow Tie Asymmetry", Penny organizes picking up the relatives and is overloaded by Amy's mother's comments and personality. When the wedding is delayed due to the absence of the bride and groom she explodes when she finds them doing science instead of getting married. Sheldon agrees with Penny so the wedding starts. Penny is overwhelmed at the ceremony of her two best friends getting married.
====Rajesh Koothrappali====
Sheldon and Raj's relationship is rather complicated, but they are best friends. He seems to be the person least annoyed by Sheldon's eccentric quirks. Sheldon once offered help to Koothrappali by giving him a job under his supervision, which Raj reluctantly accepted to save him from getting deported back to India. Raj is easily annoyed with much of Sheldon's antics, but has grown accustomed to them. Before the boys went with Sheldon on the Arctic Expedition, Raj explained to Howard that the reason he puts up with Sheldon is because of his religion; 3 months of suffering at the Arctic Circle with Sheldon would mean he (Raj) would be reborn in the next life as 'a well-hung billionaire with wings'. Raj, as much as he hates Sheldon's opinions on every certain situation and his behavior, considers Sheldon as a good friend. In "The Comic-Con Conundrum", Raj appoints Sheldon is business manager since Raj has to live on his own salary. Sheldon who loves rules and conventions immediately tells Raj that he can't go to Comic-Con this that year. Raj Was the 1st of Sheldon's friends asked to stand in series finale.
====Howard Wolowitz====
Sheldon and Howard are best friends, but their relationship is extremely complicated. The relationship between the two has its ups and downs. Sheldon revealed that upon meeting Howard for the first time, Howard claimed that Sheldon looked like a cross between C-3PO and Peewee Herman, calling Sheldon C-3P-wee Herman. Sheldon in turn often makes fun of Howard for not having a Doctorate, his clothes, going to MIT and being an engineer. In "The Bozeman Reaction", Sheldon refers to Leonard, Penny and Raj as his three closest friends and Howard as a "treasured acquaintance". In "The Parking Spot Escalation", they fight after Howard acquired Sheldon's parking spot (which Sheldon didn't need since he doesn't have a car). Their fight escalated and Amy and Bernadette go after each other, with Penny being injured. Finally Raj gets Howard to give up his space, but Sheldon, not wanting Howard to be the better man, lets Howard use it until he gets a car or a Batmobile.
However, Sheldon has shown he cares for Howard at times, letting him sit in his spot in "The Apology Insufficiency" to make up for revealing details to the FBI that prevent Howard from obtaining a much needed security clearance, and insisting Howard had a beverage to help him after an argument with his mother. Howard, much like Raj and Leonard, are quite used to Sheldon's inflated ego. Howard tried to help Sheldon learn to drive on a car simulator he created, and Sheldon has helped with Howard's creations. In "The Friendship Turbulence", their relationship improves and the two make an effort to be better friends to each other and not insult one another so often, and the two admit that they love each other as friends and their lives would be empty without each other. In "The Comic Book Store Regeneration", when Howard's mother died, Sheldon (surprisingly) comforts Howard by reminding him he has friends who will be there for him, something Sheldon did not have when his father died. These words cause Howard to smile at Sheldon and silently thank him for his words. 
In "The Application Deterioration" Howard isn't allowed to benefit from the profits of their mutually developed guidance system since he isn't an employee of Caltech. Leonard and Sheldon decide to split all their profits three ways and Sheldon even gives a portion of his share to Howard's unborn child's college fund. He doesn't want the kid to end up an engineer.
In "The Explosion Implosion", Howard is worried about knowing enough to raise a boy, but then realizes that they could bond over launching model rockets. Sheldon also gets excited about it and they take a Saturn V model out to the desert to launch. The model rocket blows up disappointing Howard until Sheldon tells Howard that he thinks that he'll be a great father especially since Howard lost his.
In Sheldon's wedding, Howard got Mark Hamill for the latter's wedding and Sheldon was grateful to him.
In "The Imitation Perturbation", on Halloween at work Howard dressed up as Sheldon, but Sheldon was clueless as to the impersonation. After he realizes it, he sees that everyone is laughing at his idiosyncrasies. Later at the party, Sheldon and Amy show up dressed as Howard and Bernadette. Bernadette is not happy with Amy's high squeaky voice and cracks about her small body. Later Sheldon does apologize to Bernie and the bond over both being small in high school. Sheldon was only eleven.
In "The Meteorite Manifestation", the Wolowitzes are having a problem with their neighbors' new deck and the floodlights that light up their backyard. Sheldon helps them with the paperwork at the city zoning office and makes their neighbors tear down their deck. The Wolowitzes deny knowing who filed the paper work. Sheldon was not happy that he learned that they had made other home improvements without the proper paperwork. He decides to take friendship over the law for once.
He treats Howard's kids better than Beverly treated Leonard. In the series finale, Sheldon called Howard his friend Astronaut Howard Wolowitz.
====Bernadette Rostenkowski====
Of the group, Bernadette is the most patient with Sheldon's quirks and personality and often knows how to handle him and they are best friends. This action is most likely due to her experience in dealing with stubborn children. For instance, in "The Einstein Approximation", she is able to send Sheldon to bed with a few stern words, much to the surprise of the group. On another occasion, she was able to help him overcome his ornithophobia in "The Ornithophobia Diffusion", by persuading him to stroke the bird he was scared of. Finally, in "The Hawking Excitation", when Howard was getting his own back on Sheldon by being mean to him, she argued that he was being mean himself and stated, "Sheldon doesn't know when he's being mean because the part of his brain that should know is getting a wedgie from the rest of his brain," before ordering him to stop with his actions, with the exception of using Sheldon to get out of having to go dress shopping with Mrs. Wolowitz. In "The Clean Room Infiltration", Bernadette takes Sheldon to Amy's Christmas dinner, while singing cheery Christmas songs at the top of her lungs. Sheldon gets tired of it and turns off the music. She also takes him to the mall so Sheldon can buy a present to get revenge on Amy for kissing him in public. The evil plan backfires and Amy loves it. Sheldon also shows a great affection for Amy and admits that he loves her impressing Bernadette. Later, in "The Fermentation Bifurcation", when everyone else is at a wine tasting in Napa Valley, Bernadette (who was still pregnant at the time) spends the day with Sheldon, and ends up having a great time. In "The Collaboration Contamination", while Howard and Amy are working together both Sheldon and Bernadette start feeling neglected. Sheldon visits to complain to Bernadette and she tricks him into doing all the chores that Howard should be doing. He also seeks advise from her as part of "Sheldon Cooper's Council of Ladies" and when he is broken up with Amy AND Penny is not available.
Although Sheldon is rude to his friends, Bernadette is an exception as Sheldon is very afraid of her and he will face her wrath if he is rude to her, a fact confirmed by Howard, although Sheldon was rude to her once when he was sick. , which upset both Bernadette and Howard so much, but Sheldon apologized to her when Sheldon learned that he was excluded from the Las Vegas trip when he upset his friends when he was rude to them while he was sick.
====Bert Kibbler====
Sheldon treats Bert the same way he treats Howard, though this is due to Bert being a geologist, a science profession that Sheldon despises.
In "The Geology Methodology", Bert asks Sheldon to collaborate with him on a dark matter project involving meteorites which Sheldon likes, but is embarrassed to tell others about. When Bert learns this he stops working with Sheldon and replaces him with Leonard.
In "The Imitation Perturbation", Bert joins the halloween custom party to which he watches a fight between Sheldon and Amy and Howard and Bernadette, It started when Howard dressed up as Sheldon in an attempt to mock him, the couple then goes to the party later dressed up as Howard and Bernadette, mocking them, Bert asks Stuart if this was a good party to which Stuart says oh yeah.
====Wil Wheaton====
Growing up, Sheldon idolized Wil Wheaton. Wesley Crusher, Wil Wheaton's character on "Star Trek: The Next Generation", had an eidetic (photographic) memory just like him. Sheldon was such a fan that in 1995, he traveled ten hours by bus to the fourth annual Dixie-Trek Convention in Jackson, Mississippi, wearing his Star Fleet Academy cadet uniform in order to meet Wil Wheaton and get him to autograph his mint in-package Wesley Crusher action figure. However, his arduous journey, during which he had to twice violate his personal rule against relieving himself on board a moving vehicle, was for naught; although advertised to appear, he did not show up. It was at that moment, he vowed eternal hatred for Wil Wheaton.
In "The Creepy Candy Coating Corollary", Sheldon entered a Mystic Warlords of Ka'a tournament with Raj at Stuart's comic book shop in hopes of battling Wheaton, and put his name on the sign-up sheet as "DIE WILL WHEATON DIE". During this tournament, Sheldon utters in Klingon to Wheaton from across the room, "Revenge is a dish best served cold." When Raj and Sheldon get to the final round, they must face Wil and Stuart. Sheldon explains logically what cards must be in Wheaton's hand and how he is able to beat them. After Sheldon informs Wheaton why he hates him, Wil claims his grandma had died. Sheldon falls for the ruse and throws the game, only to learn shortly thereafter that he had lied, causing him to reaffirm Wheaton's status as his mortal enemy in a display of rage akin to Adm. Captain Kirk's reaction towards Khan's threat of marooning him on Regula in the Star Trek II: The Wrath of Khan. His true reason for not showing up is revealed in "The Russian Rocket Reaction"—he was on "Hollywood Squares".
Wheaton messed with Sheldon in a bowling game in S03E19 "The Wheaton Recurrence". During said game, Sheldon named his team "The Wesley Crushers". In this encounter, Wheaton also managed to cause Penny to break up with Leonard through deceit, by upsetting Penny (who was on Sheldon's bowling team) enough to make her leave the bowling alley, Wheaton's team would go on to win the bowling match over Sheldon's team.
Wheaton appears again in "The 21-Second Excitation" at a showing of the movie, "Raiders of the Lost Ark," with 21 seconds of deleted footage. After Wheaton and his crew were allowed to cut in line by the security guard, Sheldon exclaimed with his impersonation of Patrick Stewart's accent, "As Captain Jean-Luc Picard once said, the line must be drawn here... THIS far, NO farther!" Wheaton later boasted about his great seats and told Sheldon to 'suck it' via Twitter. When Sheldon, Leonard, Raj and Howard were eventually denied entrance to the theater, Sheldon stole the film cans containing the footage, resulting in an angry mob led by Wheaton chasing the four out of the theater.
In "The Russian Rocket Reaction", Wheaton invited Leonard and Sheldon to his place for a party. Here, Wheaton gave Sheldon his last mint condition, autographed Wesley Crusher action figure. While Sheldon forgave and hugged Wil Wheaton, Brent Spiner (who played Lt. Data in Star Trek: Next Generation) approached them, saying he "hadn't seen one of these Wesley Crusher Action Figures in ages," and proceeded to take the mint-condition-still-in-box action figure away from Sheldon. After tearing the packaging, Spiner became Sheldon's new mortal enemy.
In "The Proton Regeneration", Wil is up to compete with Sheldon for the role of Professor Proton in the show's reboot. Unfortunately, Wil Wheaton ends up getting the role of Professor Proton on the reboot which upsets Sheldon and he tries to get the guys to call in displeasure in hopes of getting the reboot cancelled but it doesn't work. Sheldon returns to Wil to demand that he turn down the role. Wil refuses and is on Sheldon's enemies list again.
During the rest of the series Wil Wheaton was friendly with the gang. At Sheldon's birthday party, Wil toasted Sheldon with, "You may be a fan of Star Trek, but I'm a fan of Sheldon Cooper."
====Beverly Hofstadter====
Between his neurotically strict speech patterns, lack of social conventions, and attention to detail, Sheldon is the male equivalent of Leonard's mother Beverly Hofstadter (though in many ways she surpasses him, as Sheldon can and does, admittedly rarely, show affection to others, while she never has). Sheldon did keep in touch by Skype, much to the confusion of Leonard.
Indeed, her inability to understand social conventions seems if anything to be somewhat more extreme and has to have some social concepts explained to her by, of all people, Sheldon (though his explanations typically reflect his own, at best, incomplete understanding). It's therefore unsurprising that Sheldon and Beverly share an odd non-romantic attraction to each other. They have a mutual interest in having their brains scanned and have even sung a duet of the Journey song "Any Way You Want It"; however, she did once kiss him passionately while intoxicated (declaring afterwards that she'd "rather have the busboy"). She apologized the following morning and Sheldon accepted as she was intoxicated (he blamed Penny).
Despite being equivalents, there are things that make Sheldon and Beverly different, like, for example: Unlike Beverly, Sheldon truly appreciates Leonard and is capable of love, which Beverly is severely lacking and near nonexistent.
In "The Conjugal Conjecture", Beverly actually snaps at Sheldon when he acts crazy after hearing that her ex-husband is probably hooking up with Sheldon's mother, her maternal rival and then Sheldon actually talks back to Beverly, taking offense of her calling his mother a Bible thumping bumpkin though he admits her analysis is partially correct.
====Robert Wolcott====
Dr. Robert Wolcott is a brilliant but reclusive topologist, noted for Wolcott's Theorem, who has made great strides in his work on nonlinear time while ignoring the rest of the world. Sheldon Cooper has corresponded with him and is invited to his mountain cabin. The guys go with him at Amy's insistence. He lives off the land and ignores the world thus making great strides in his work. He recommends the life to Sheldon if he is really dedicated to science. Sheldon considers it, but he misses Amy and his cell phone which the paranoid doctor took from him.
====Tam====
In "The Tam Turbulence", Sheldon's high school friend is visiting Caltech and wants to see him. Sheldon still has a grudge against him because he said he would move to California with him, but stayed in Texas. Tam didn't know that Sheldon was mad at him, but they made up just before he left.
===Romances (Usually one-sided until Amy)===
Of all the main characters of the show, Sheldon is presumed to be asexual and has displayed absolutely no interest in pursuing a sexual relationship with anyone. He tries to avoid all human physical and emotional contact. He has, however, had a few opportunities to "get it on" - maybe more opportunities than the other characters. Being true to his personality, though, he never seems to realize it. The introduction of Amy Farrah Fowler has changed this aspect of him, at least slightly. Even though Amy used to be his friend, but not his girlfriend, and now is his girlfriend, she is the closest person who romantically linked to Sheldon. Though, their relationship used to be nothing more than that of friends, or, as Sheldon put it, "a relationship of the minds". Eventually, they move in together and get married.
====Lalita Gupta====
 
Lalita was arranged to be married to Raj. They went on a date together which gradually deteriorated as alcohol made him obnoxious. When Sheldon arrived at the bar, he thought she looked similar to an Indian fairy tale princess from a bedtime story his mother used to read to him when he was sick. When he told her, she was flattered and ended up dumping Raj and going out for dinner with Sheldon. When he was asked about it the next day, he simply said that they ate and discussed dental hygiene. He didn't seem to realize that he technically was on a date with her. When Leonard asked him if he was going to see her again he looked puzzled and said "Why would I see her again? I already have a dentist".
====Ramona Nowitzki====
Ramona was a huge admirer of Sheldon and had an obvious crush on him, which he didn't seem to notice. In S02E06 "The Cooper-Nowitzki Theorem", she asked him out for dinner and ends up bringing it to his apartment. After that, she began spending more and more time with him, haunting the apartment night and day walking around like the T-X terminator from "Terminator 3: Rise of the Machines." Ramona becomes a platonic girlfriend and research assistant even spending nights on the couch. She prevented Sheldon from doing anything recreational like playing Halo, paintball or watching Battlestar Galactica so he could focus on his work that he was so enamored with. Eventually, he made a breakthrough. When she suggested they share credit, he simply responded "Get out!", after which she angrily left.
In season 11, she returns to Caltech pursuing Sheldon while Amy is away for the summer in New Jersey. Penny has to point out the romantic attachment she has. After Ramona kisses him, he runs to New Jersey to propose to Amy. When Amy confronts Ramona, she thanks her for pushing him to propose, leading to an awkward hug.
====Kathy O'Brien====
 
In "The Cooper-Nowitzki Theorem," after the affair with Ramona Nowitzki, there is a brief incident in the Caltech cafeteria that appears to be the beginning of the same kind of relationship with a different grad student, Kathy O'Brien. Like before she is impressed with his work and want to talk with him. She agrees to bring over pizza to his apartment. And she already has his address.
====Martha====
 
When Raj brought Sheldon to a faculty mixer to act as wingman in S03E12 "The Psychic Vortex", they picked up a girl named Abby (Danica McKellar) and her friend, Martha (Jen Drohan), brought them to Sheldon and Leonard's apartment and played Rock Band with them. While Abby and Raj hit it off, Martha became interested in Sheldon. The two enjoyed a few stimulating discussions together at their second meeting, during which Raj and Abby, "were getting busy in the living room," Sheldon was either unaware or disregarded her interest in him before he went to bed. Martha visited Sheldon's room in the middle of the night and she asked to come in, hoping for sex. Misinterpreting this, Sheldon went to sleep in Leonard's room and left Martha alone in his room.
====Amy Farrah Fowler====
=====Season 3=====
Sheldon first met Amy via a dating site where Howard and Raj sneakily set up an account for him in the season 3 finale, "The Lunar Excitation". Eventually, they found a perfect match for him and agreed to meet her at a café. When they told Sheldon, he refused to do it, believing dating sites to be "hokum". He was blackmailed into doing it when Raj said he had hidden a dirty sock in his apartment and would not remove it unless Sheldon went on the date. When they arrived, Sheldon had doubts until he met Amy, who acted exactly like Sheldon. She only agreed to come on the date as she and her mother have an agreement that Amy would date at least once a year. Sheldon had the same agreement with his mother about church; therefore, they bonded over their relationships with their mothers. Sheldon noted they had a lot in common and bought her a beverage of tepid water. Raj and Howard regretted what they had done, with Howard saying, "Good God, what have we done?"
=====Season 4=====
In the season 4 premiere, "The Robotic Manipulation," Sheldon reveals that he has been talking to Amy for four months online and via text messaging, after they first met. Penny is amazed that Sheldon has a girlfriend and Howard and Raj call Sheldon and Amy, "Shamy." Sheldon denies that Amy is his girlfriend and that they mainly talk about Sheldon's theoretical physics, Amy's neurobiology and the possibility of having a child together via in-vitro fertilization. Penny convinces Sheldon to go on a proper date with Amy first, before he actually decides to have a child. She ends up on the date with them, as she had to drive them to the restaurant. While there, Penny tries to make conversation, but fails. After the subject of Sheldon's first date comes up, Sheldon calculates the number of men Penny would have dated. He ends up with 193, with 31 sexual encounters. Amy then innocently asks if Penny feels like a "slut" and reveals that she has had 128 sexual encounters (if you include stimulation of the brain to induce orgasm). Eventually, Penny convinces Sheldon not to have a child with Amy by threatening to tell Sheldon's highly-religious mother; who would likely frown upon a test tube, surrogate, out-of-wedlock grandchild.
In episode 3 of season 4, "The Zazzy Substitution", Amy and Sheldon breakup for a period of time after an argument over whose field of science is superior. This results in Sheldon buying a clowder of 25 cats, which worries Leonard. So he calls Sheldon's mother, who is unusually surprised at what she sees with Sheldon. She then calls Amy and uses the technique of reverse psychology which Leonard instantly picks up on, but Sheldon is completely oblivious to. She tells Sheldon that it was a good thing he and Amy broke up because they are completely incompatible. Sheldon is instantly offended, so to prove his mother wrong, he offers Amy to reconcile, which she agrees after a negotiation on the amount of responsibility Sheldon has to accept for the break up (Amy offered 80%, Sheldon countered with 40%, settling at 65%). Afterwards, Sheldon pays anyone $20 willing to adopt his cats.
In episode 5 of season 4, "The Desperation Emanation", Amy requests Sheldon to meet her mother, which terrifies him after Leonard tells him that their relationship has stepped up. He tries many ways to avoid her, as he thinks she has fallen in love with him. Amy says that she only wants to be friends with Sheldon and wants to pretend to be Boyfriend/Girlfriend to please her mother so that she will be silent on that matter. Sheldon freaks out Amy's mother a bit, which is what Amy wanted him to do, when they tell her about their "fake" sex life. Her relationship with Sheldon is complex; it began as a purely intellectual friendship which consisted solely of text messaging, but at some urging from Penny, develops into a platonic friendship with dynamics similar to a romantic relationship, although not sexually intimate.
They later pretend to have had a sexual encounter (the made-up details of which included Amy becoming pregnant) as an experiment to see how long it would take the gossip to spread throughout their social circle, which Sheldon notes was "less than 24 hours." In "The Agreement Dissection", she became drunk during a "girl's night" with Penny and Bernadette, at which Sheldon was present to escape Priya, and danced eccentrically with Sheldon, after which Sheldon walked her home. She invites him in and, after advising him on how to deal with Priya, flirts with and then kisses Sheldon to which he responds "fascinating". After she throws up and passes out, Sheldon puts a towel under her head as a pillow and leaves (before doing this he regulated Amy's kitchen timer, which was making him go crazy).
The next morning, a hungover Amy video-calls Sheldon, and he informs her of the kiss, and when Amy admits she is unsure where to go from there, they agree to pretend the entire events of the evening never occurred.
=====Season 5=====
Amy invites Leonard to a wedding, explaining that she'd invited Sheldon before, but he "acted like a child." She and Leonard end up having a rather good time, though by the end of the night he'd sprained his groin dancing the Hokey Pokey and she's convinced Leonard is in love with her; however, when Leonard tells Sheldon about the night, the way he describes it makes it seem as though he and Amy had sex. Sheldon bops Leonard rather hard on the shoulder, and states very firmly that Amy is not Leonard's (She is not for you; not for you!), leaving his friend totally confused.
In "The Isolation Permutation", Amy got depressed after Penny and Bernadette went bridesmaid dress shopping without her and Sheldon ended up comforting her. First she asked for sex due to wanting physical intimacy, the couple made counter offers and settled with cuddling, something Sheldon was reluctant to do.
A recurring topic for discussion among the audience of the show is whether Amy may be the first person that Sheldon may have developed romantic feelings for, though he himself may not have realized it yet. It is clear that Amy is attracted to Sheldon, as witnessed in her many attempts to have some form of physical contact with him, such as kissing him while she was drunk, holding his hand and said that it was an experiment, and during the counter offers, she attempted to get Sheldon to agree to get into bed with her or possibly French-kissing. She can also be seen smiling in his presence when they first meet as the scene ends. Amy had also, in a scene in Season 5's "The Pulled Groin Extrapolation", told Leonard at a wedding that she has "a kinda-sorta-boyfriend playing with a model train and you don't hear me bitching about it", a clear reference to Sheldon. In "The Ornithophobia Diffusion", when Sheldon finally overcame his fear of birds and appeared infatuated by the bird, to the point he called him his little "Lovey-dovey" a slightly jealous Amy replied "guess you gotta have hollow bones to get some sugar around here".
Sheldon, while his feelings for Amy remain ambiguous, clearly cares for her. In "The Isolation Permutation", several events highlighted his care for Amy. When a devastated Amy wanted to be alone and did not respond to any form of communication Sheldon attempted to reach her, Sheldon grew worried and distracted, till Leonard suggested that they go over to her place to check up on her. While getting ready to leave their apartment, Sheldon shared news that a bobcat was spotted near Amy's place and Leonard responded that he does not think that Amy has been eaten by a bobcat. A shocked Sheldon said that he was only sharing a piece of news and now, thanks to Leonard, he is worried whether Amy has indeed been eaten by a bobcat. Later, at Amy's apartment, when she told Sheldon that she wanted to be left alone, Sheldon asked, rather awkwardly whether Amy would like to talk about what's troubling her, though he did add that he has no problem if Amy says no. Afterwards, when Amy counter-offered with him regarding human intimacy and physical contact, Sheldon eventually agreed to cuddle with her. When a drunk Amy called Sheldon as he was building his Lego Death Star, he and Leonard went to see her in a liquor store parking lot when she called Leonard "Lil' Leonard" and Sheldon "Cuddles", a term which earned a frown from Leonard. Sheldon quickly retorted with "Yes, Cuddles. We cuddled. Grow up Leonard!", showing that he no longer cares about what his friends may say regarding his relationship with Amy.
In "The Flaming Spittoon Acquisition", Sheldon at first claimed he was fine with Stuart asking Amy out on a date. Later, when he went to the comic book store with Leonard to return Leonard's Wild West and Witches expansion pack and found that someone else has replaced Stuart since he is out for coffee with Amy, he started feeling jealous. Leonard asked him whether he was okay, but his reassurance on the matter looked doubtful. At the university cafeteria, as the guys were discussing the Wild West and Witches deluxe set, Sheldon was checking Stuart's Facebook page, and the guys were surprised to see that he has actually friended Stuart. Raj suggested that he did so just to keep tabs on Stuart's date with Amy. Leonard told him to acknowledge his feelings for Amy while Howard told him to challenge Stuart to a fight. Sheldon said that he could not care less about the date, but ended up unfriending all three of them. Later, he went to Penny's apartment and asked Penny out on a date, to signal that he did not care about Amy and Stuart. When Penny told him that he only wanted to do so to make Amy jealous, he denied and wondered why everyone else is obsessed with Amy and Stuart and added whether those two have more pumpkin lattes or will have intercourse, showing that he did keep himself updated with the details of their date(s). Penny told him to buck up and talk to Amy.
Sheldon ended up interrupting Amy and Stuart's date at the movie by sitting next to Amy. When Amy asked what he was doing there, he covered up by saying that the thought of Amy sitting in a darkened theater with a character like Stuart is repellent. Amy apologized and influenced him to man up to his feelings by saying that their current relationship status allows her to be in any repellent situation she likes. This was when Sheldon decided to propose an alteration to their relationship paradigm by saying he would no longer object if they characterize her as his girlfriend, but other than that, nothing will change in terms of physical or otherwise. Amy pushed Sheldon to try saying that again without the negative, but he refused so she provoked him by sliding towards Stuart and saying "hi" to him, following which Sheldon relented and asked properly if Amy is willing to be his girlfriend. She agreed and he left immediately. Later on, Sheldon waited inside Amy's apartment as she finishes her date. When Amy and Stuart was conversing outside her apartment, Sheldon told them to quickly wrap things up and when Amy and Stuart gave each other a friendly hug, Sheldon immediately retaliated by asking Stuart to take the hint that Amy has said "goodnight". When Amy asked him how he entered her apartment, he complained whether she will keep nagging like this now that she is his girlfriend and introduced her to The Relationship Agreement. Amy did not seem to like the agreement although she said it is romantic. Sheldon told her she could get herself a lawyer. Amy agreed to the agreement anyway making them officially a couple.
In "The Beta Test Initiation", Amy helped Sheldon with his Internet series on vexillology entitled "Fun With Flags". At the beginning, she even made a suggestion, which Sheldon described as brilliant (highly unusual, since he normally dismisses other people's comments about his work though he is willing to listen to her). In one episode where Sheldon was describing the Bavarian flag, he even dressed up as a Bavarian and Amy dressed up as a pretzel.
In "The Friendship Contraction", Sheldon asked Amy to take him to the dentist after all of his other friends refused after Leonard had signed the clause on The Roommate Agreement to reduce his and Sheldon's relationship to mere acquaintances. Amy was busy with work and could not drive him. He tried to make her guilty by telling her that as his girlfriend, she had to cater to his needs, and even to the extent of asking her "Where has the magic gone?" Amy looked upset at his comments and Penny ended up defending her.
In "The Vacation Solution", Sheldon decided to work at Amy's laboratory with her for a week, after he was forced to undergo his mandatory vacation. Once there, he was appalled by the tasks Amy told him to do, which were menial given his standards, such as washing the beakers and counting spores. Surprisingly, he could not accomplish any of the tasks right. Eventually, he confronted her on the matter. Amy reasoned that even if he was a genius, she could not assign him difficult tasks because he had no experience working in biology. Sheldon retaliated by telling her that she was just afraid that he would be better than her. Annoyed, Amy let him slice the brain specimen she was working on. He ended up cutting his thumb and fainting at the sight of his own blood. After talking to Penny, Sheldon went back to apologize to Amy for his behavior; however, being Sheldon; he could not offer a sincere and direct apology. Amy downright refused to accept anything, but a real apology so finally; he managed to mutter up a short "sorry". Amy accepted and told him to start washing the beakers again.
In "The Werewolf Transformation", Sheldon missed out on his regular haircut schedule, due to his regular barber being hospitalized. This event affected his daily routine because he could not get over not getting his haircut on time. When he was over at Amy's apartment, on their scheduled "girlfriend-boyfriend sing-a-long night", he could not concentrate. Amy suggested he go to Supercuts, but he refused, equating Supercuts to "Sodom and Gomorrah with mousse". She then suggested he grew out his hair, because she thought he would look sexy with long hair. He refused to that as well. Later, Sheldon spiraled even more out of control by playing bongos at 3 a.m. and went over to her apartment. The next day, when Leonard and Penny came over to pick him up, Amy revealed that she initially thought Sheldon's presence last night was a musical booty call. Sheldon finally relented to have his hair cut by Penny, after Amy convinced him by saying that there was no hair on her body she would not let Penny trim.
In "The Weekend Vortex", Sheldon agreed to go to Amy's aunt Flora's 93rd birthday party. He began to have doubts on going after the guys told him that they would be having a 48-hour Star Wars online gaming marathon, like in the old days. He tried to persuade Amy to let him stay instead, but she refused, saying that she followed all his protocols in The Relationship Agreement. Sheldon gave in, albeit unwillingly. The next day, when they were about to begin their journey, Amy discovered that Sheldon had brought along his laptop with him. Sheldon told her that he had found a way to compromise, by being physically present at her aunt's party, but virtually present for the online gaming. Amy told him that it would make him appear rude since her family would want to talk to him. He told her that he will have his headset on so that he could not hear them in the first place. Upset, Amy sarcastically told him that if gaming was more important to him than his commitments to her, he could stay. He did not get her meaning and opted to stay. Amy was later seen upset having gone to the party alone. She confided in Penny and Penny persuaded her to make a scene. The girls later barged into Sheldon and Leonard's apartment, while they were still gaming. Amy told Sheldon that she was going to embarrass him in front of his friends. She told him that she was leaving him for Arman, the miniature horse breeder. He asked her who Arman was, but she tripped up on her words and failed to continue the ruse. Penny helped by telling Sheldon he hurt her by backing out on his words. Sheldon finally understood her and offered her Cooper Coupons to make it up to her. They left to visit the science museum.
In "The Launch Acceleration", Sheldon came over to Amy's apartment for their scheduled monthly Date Night for a home-cooked dinner, despite his idea of a hot date is crossing the street and going to the Lego store to buy a tiny Lego Indiana Jones. He found out that the reason Amy requested to have their Date Night at her place was to get their relationship moving forward, just like their friends'. He was reluctant because he thought that considering he has known her for two years and he was already at her place after dark, their relationship could not go any faster. However, Amy, having anticipated his response decided to achieve her goal by using her skills in neurobiology. She wanted to try to create his emotional attachment to her, just like his attachments to his
mother and superheroes, by making him happy. Their Date Night was full of the things he likes, such as Super Mario Brothers' theme song as the background music, drinking strawberry Quik, and being served spaghetti with little hot dogs cut up in it. Amy's plan seemed to be going well because Sheldon immediately responded with they should do it more often. After the night, it was shown that Sheldon had become distracted and he admitted to Leonard over their game of 3D chess that he was starting to develop affectionate feelings for Amy at inappropriate times, though not in a sexual way. He also revealed that Amy took her campaign even further past their Date Night by arranging for him to become an Amtrak junior conductor, something extremely special since it was only open for kids. He even got to blow the whistle. At the end of the episode, Sheldon and Amy were caught by Leonard playing Doctor, Star Trek style, with Sheldon lying on the couch while Amy, fully dressed in a Nurse Chapel uniform from Star Trek: The Original Series, performed medical check-up on him.
In "The Countdown Reflection", Amy told Bernadette that she thinks Sheldon's eidetic memory is sexy and proceeded to ask him to recite the ingredients in Pringles. Later, at the City Hall while waiting for Howard and Bernadette to get married (they did not however, manage to squeeze in for the day), Amy asked Sheldon whether being at there and witnessing a lot of couple in love makes him thinking, but he did not get what she meant and ended up exposing Leonard's failed proposal to Penny in the previous episode to all their friends. During the wedding ceremony, as Sheldon was addressing Howard and Bernadette, Amy looked displeased when Sheldon told them that he hopes they find happiness together as he has found being all by himself. However, during Howard's launch into space, Sheldon did something completely contradictory to his statement, by grabbing Amy's hand as he said "Boldly go, Howard Wolowitz".
=====Season 6=====
At the beginning of season six, Amy and Sheldon are shown regularly dating in "The Date Night Variable". Sheldon invites Raj along for their second anniversary dinner much to Amy's annoyance. After Raj leaves, Amy demands a statement from the heart from Sheldon or she was leaving him. Sheldon provided some paraphrased romantic dialogue from the first Spider-Man (2002 film) movie. Amy says that she'll "take it". In "The Decoupling Fluctuation", at the movies, Amy requires Sheldon to now hold her hand though Sheldon thinks the idea is silly and unhygienic. In "The Habitation Configuration", Amy is directing an episode of "Fun with Flags" guest starring Wil Wheaton. While not liking his acting, the two get into an argument and Amy leaves. Sheldon is first caught in the middle and then naively thinks that Amy is solving the problem by leaving. He eventually learns that he should support Amy in disagreements.
In "The Parking Spot Escalation", Amy backs up Sheldon in his fight for Howard's parking place, helping him put his name back on the space and leaving her car parked in it. After she finds it towed she confronts Bernadette and ends up smashing her "bestie", Penny, in her face breaking her nose. The next episode "The Fish Guts Displacement", Sheldon finds Amy has the flu and she asks him to take care of her per their Relationship Agreement. First Sheldon says that that is meant for her to take care of him and then leaves. Moments later Sheldon has a change of heart and tells her that they have a written agreement and that he cares about her wellbeing so he will take care of her though he wants her to get through it quickly. Later when he finds that her temperature hasn't gone down, he tells he that she isn't trying. Amy complains about his bedside manner and just wants to go to sleep. Sheldon says that that is not acceptable because he isn't through taking care of her. He has to put a rag on her forehead, sing to her (probably Soft Kitty) and rub Vicks vapor rub on her chest. Sick Amy sits up surprised and wants to start with the Vicks with Sheldon not realizing the sexual aspects. Sheldon tells her that it may tingle and Amy replies that she is counting on that. A few days later Bernadette visits her and learns that Amy is feeling fine and is enjoying Sheldon taking care of her especially since he has started bathing her. A couple of days later Sheldon has the results of a throat culture which says that she is no longer sick. Amy apologizes. Sheldon is disappointed because he thought their relationship was based on trust and mutual respect. He says that she needs to be punished so that that doesn't happen again. She thinks she should not be allowed to see the next Star Trek movie, but Sheldon feels that that is too harsh a punishment. He prefers being put in the stocks in public, but doesn't think that he needs a permit for that. Instead he decides to give her a spanking which she enjoys. In "The Cooper/Kripke Inversion", Sheldon lies to Kripke about sleeping with Amy after Kripke performs better than him on a project they were working on together. Also, Sheldon enjoys being held and consoled by Amy when he is very upset about Kripke. In "The Spoiler Alert Segmentation", Leonard moves out and Amy tries to convince him that she would be his ideal new roommate. She is familiar with all his habits and his personality quirks that others fine rave inducing, she thinks are cute as a button. Sheldon is uncomfortable with this much increased intimacy with Amy and also learns from Penny that she doesn't want Leonard to move in with her. Sheldon finally tells Amy that she can't move in and that it's Penny's fault. Amy confronts Penny who tells Sheldon why he didn't tell Amy that he didn't want her to move in instead of blaming it on her. Amy calls Sheldon a coward, which he agrees with and Amy goes off to (tentatively) live with Penny. In "The Tangible Affection Proof", Sheldon has Alex buy Amy her Valentine's Day gift and she does such a great job with her third option, the signed brain cell print that Sheldon keeps it. Amy shows up after canceling their romantic dinner and tells him that they'll eat pizza and watch one of his Star Trek/War movies since that is what he really loves. Sheldon shows Amy that she is now his emergency point of contact at the university which sends Amy into tears. He really trusts her.
In "The Love Spell Potential", after Amy was upset about the notion that their D&D characters should have sex, as it was not going to happen in real life, Sheldon was sent to comfort her. Although initially unwilling, he listened to her complain about how the others thought their relationship was a joke. Sheldon responded by saying he didn't think that. Amy asked him if they would ever have an intimate relationship. Sheldon sat down and told her before he met her; he wasn't interested in being intimate with anyone. Amy prompted him to see if he felt any differently now, and he admitted it was a possibility. This didn't really cheer her up, so he explained to her that although it didn't feel like it to her; to him it did feel really intimate. Amy knew this, but said she just wished she could have more. Sheldon managed to cheer her up, by pointing out that they had only known each other for three years and they were already in bed with each other (technically sitting on Sheldon's bed). Amy said they should go back to the others, but Sheldon stopped her, and very calmly pointed out that as they had had love spell put on their characters in the game, it would only be right to carry it on. And so alone in his room, away from all others, he allowed her to experience a form of virtual intimacy, using a dice to decide what to do next, upon getting a throw she didn't like he was willing to break the rules and throw again (which for him is quite impressive). The two were still playing a while later, and had apparently progressed a long way when Leonard and Penny went to check on them and were told to go away.
=====Season 7=====
In "The Deception Verification", Amy and Sheldon conclude that Penny is cheating on Leonard, so Sheldon decides to rush into Penny's apartment and catch her with the other guy. Amy does not recommend this action. When he does, he finds Leonard secretly hiding out to be with Penny, making Sheldon mad at Leonard. When he also vents his anger on Penny, Amy defends her. Sheldon warns her that the girlfriend of my enemy's girlfriend is also my enemy. Amy pulls her offer of a ride and Sheldon claims that there must be a third option or exception for Amy. He needs the ride since he's mad at Leonard.
In "The Raiders Minimization", Sheldon offers Amy to lose her virginity; however, it was for her first viewing of one of his favorite movies, "Raiders of the Lost Ark". She enjoys it, but points out that the plot would still work without the main character. Since she spoiled the movie for him, and later the whole group, he tries to find something to spoil that she likes. First he reads "Pride and Prejudice," declaring it a timeless masterpiece, and then he looks into the comics page. Finally, they start watching her childhood favorite show, "Little House on the Prairie" and he keeps pointing out inaccuracies. She quickly picks up on what he is doing and tells him that since they are in a relationship, he should tell her when he is angry with her. They both apologize, though he still tells her what is wrong with the comic strip Garfield, showing that they still take one step backwards. 
In "The Workplace Proximity", Amy starts working at Caltech which does not bother Sheldon at first. After Howard's comments how he would not want to work all day near Bernadette, Sheldon withdraws his approval though Amy still plans to work there. Embarrassing Amy in front of her co-workers at lunch with inappropriate ethnic comments and talking about the status of their relationship, Amy is extremely unhappy with him. Late at night he comes to her apartment to apologize. She calls her something of a weirdo. They do manage to say that they like each other quirks and all. Sheldon then ruins the moment by adding that she should like him since he doesn't see anyone else knocking at her door. Later Amy tells Penny and Bernadette that she is not apologizing to Sheldon.
In "The Romance Resonance", Sheldon makes a great scientific discovery of a new superheavy element which thrills Sheldon until he realizes he made a bone-headed error in his calculations. Everyone still praises him, much to his annoyance. Amy first tries to soothe him like everyone else until she finally agrees with him taking his side. Sheldon tells her that that is the most romantic thing he has ever heard which pleases Amy. Later when it looks like Sheldon is about to actually kiss Amy, Amy comes out of "the zone" and her wishful daydream.
In "The Thanksgiving Decoupling", when Sheldon doesn't want to go to Mrs. Wolowitz's for Thanksgiving, he starts to compare his life to that of a black man being taken from Africa and being sold as a slave in America. Amy tells him that he can't say that because it is inappropriate, he responds by saying "Yes, Miss Amy." When Amy hears that a drunken Sheldon has been mean to Howard she demands he apologize, he relents and says that he is sorry. Afterwards he looks at Amy and then says to everyone "Ain't she great?" Amy is flattered and smiles. Sheldon then abruptly says "Now, how's about you get us a couple of beers?" and follows by smacking her rear. Amy, shocked, starts to walk slowly toward the kitchen as a dazed smile slowly appears on her face. Amy looks back at Sheldon, who smiles back wholeheartedly.
In "The Cooper Extraction", Amy points out to the gang that most of them would not know each other if Sheldon had not been part of their lives. Amy envisions herself crying and alone on her birthday with a cupcake and a single candle. To cheer her up, Leonard shows her Sheldon's screen saver that includes a picture of her. After he returns, she is very happy to see him and asks about how he felt holding a baby. Sheldon felt the baby didn't understand him better than anybody else. Sheldon was in Texas helping his sister in the birth of his nephew, much to his disgust.
In "The Locomotive Manipulation", Amy arranges for a Valentine's Day weekend trip to a Napa Valley bed and breakfast inn for the two of them. They will travel on a vintage train and have a romantic dinner together. To make Sheldon more comfortable they are traveling with Howard and Bernadette and they will have separate rooms. After Sheldon tells her that she is manipulating him, Amy admits that she was only looking for some romance. Insulted, Sheldon tells her that he will give her romance. To fulfill his list of romantic things, he drinks his wine which burns, stares into her eyes momentarily until she blinks and loses and then kisses her. Though it was meant to be quick and sarcastic, Sheldon seems to enjoy it and lingers. He first leans over and then puts his arms around Amy. Amy is too shock to hug him back. Amy then tells him that it was nice. Sheldon wants to leave to again talk to the conductor. Amy still breathless from the kiss tells him to have a good time. Then Sheldon invites her to go with him.
In "The Table Polarization", the gang wants to add a dining room table to Apartment 4A which as usual Sheldon-like since he doesn't want things changed. Sheldon objects to Penny changing Leonard to stand up against him. Penny points out that Amy has changed Sheldon who agrees and then decides to breakup with Amy. Amy is alerted and deals with it by agreeing with Sheldon to breakup and that Leonard is manipulating him to breakup with her though she clearly knows him and is manipulating him. She goes with him supporting his fight against that awful table and is feeding him his lines. He stops when she includes that he is moving in with his girlfriend.
In "The Indecision Amalgamation", Sheldon is obsessed with his video game system decision and rambles on about his options while having their date night dinner at Amy's apartment. She fakes an interest in his problem after Sheldon thinks she isn't paying him enough attention. Finally she screams at him, "Please pass the butter!" after he constantly ignores her request. Still mulling over his decision at Best Buy, Amy almost falls asleep on his shoulder.
In "The Anything Can Happen Thursday Recurrence", Penny takes Sheldon to a psychic at a time when he can't decide what new problem of science to follow after string theory is disproven. The psychic knows that he has trouble with his girl and that following that relationship will give him the answers he seeks. Amy lies to him about being sick when she goes out to dinner with Bernadette who are both tired of his complaining about string theory. She makes it up to him like Bernadette does to Howard by showing up in a Catholic school girl's school uniform. He is not impressed unless she has a Blu-ray DVD of the film "Gravity".
In "The Status Quo Combustion", Sheldon is disturbed by the university telling him he can't change his field of study, Leonard's comment that he doesn't want Sheldon to live with him and Penny and the comic book store fire. Amy tells him that living alone might be good for him and if that doesn't work, he could move in with her. Pushing him even further, Sheldon decides to leave town to think things over without telling Amy. When talking over his problems with Stuart, he admits that Amy loves him. The next day, he calls Amy and she thinks he sounds like he's doing fine. Penny and Leonard assure him that it's for the best, and then Amy starts hitting Leonard with a pillow telling him that he should not have let Sheldon go.
=====Season 8=====
In "The Locomotion Interruption", Sheldon has traveled around the US for 45 days winding up in Kingman, Arizona after all his possessions and his pants had been stolen. He calls Leonard to come and get him. Amy comes along very upset about having not been called by Sheldon and about him never having told her goodbye before he left. Sheldon did not want Amy to know that he had failed in his journey and that she would think less of him which touched Amy. She told him that she is okay with her that he was not perfect. Still unhappy about his unsuccessful trip, Amy told him to consider that it was an adventure which Sheldon accepts. He now feels confident to take on any changes in his life until he finds out that Penny cut her hair.
In "The First Pitch Insufficiency", Shamy and Lenny go on a double-date where Sheldon is bragging about their relationship is so much better than theirs. Shamy has an 8.2 out of ten for relationship stability based upon well proven criteria. He also compares their Relationship Agreement to the thirteen colonies and the US Constitution. Amy is really enjoying Sheldon's comments about how great their relationship is to the point that if she was wearing flag underwear that it would be on fire.
In "The Prom Equivalency", Sheldon is worried after hearing from both Penny and Leonard that the tradition after prom is to have sex with your date. After seeing Amy in her prom dress, Sheldon runs off, distressed. Amy comes into Sheldon's room and Sheldon tells Amy about his concerns. Amy gets up to leave saying she doesn't want to miss yet another prom, and Sheldon stops her telling her that he really did think she looked pretty. Amy tells Sheldon that it is okay and he didn't have to spend the night with her unless he wanted to and that she just wanted to have a nice time at the prom. She goes on to say that she wants to tell him something and that it was okay if Sheldon didn't feel the same way. Sheldon responds by saying, "I love you too," shocking Amy. Sheldon further confesses his love saying that there is no other way to describe his feelings for her though he briefly considered it was a brain parasite. The episode ends with the happy couple taking a picture at the prom photo booth together.
In "The Clean Room Infiltration", Amy insists that Sheldon come to the Christmas Eve dinner party she is having despite his dislike for the Christmas season. She also kissed him under the mistletoe when they were Christmas tree shopping. Sheldon plots revenge against her to make her feel as miserable as he does and hopefully she will never make him celebrate Christmas again. Since they agreed to not exchange gifts, he felt that if he got her the perfect gift, it would make her miserable. He gets his picture taken with Santa and has it enclosed in a picture frame which includes a tender recorded Christmas greeting to Amy. Amy loves it and gives him a gift of some Christmas cookies that his Meemaw used to make. Sheldon is touched and wonders if Christmas isn't about giving until Raj reaches for one of his cookies. Sheldon admits to Bernadette that he loves Amy and Amy admits her love in front to the entire group.
In "The Comic Book Store Regeneration", Sheldon is mad at Amy for working with Barry Kripke in string theory and not with him. Sheldon deflects his anger by telling Penny and Leonard that Amy was doing experiments on them by giving them puzzles to do and comparing their results to her chimps and making them mad at Amy.
In "The Colonization Application", Sheldon and Amy decide to take their relationship to the next, to buy a pet together - a turtle. While picking one out Sheldon reveals that he has put in an application to be one of the first colonists on Mars. Amy is hurt that she didn't consult first with her since she thought they were planning their future together AND on the same planet. Sheldon then asks Amy to join him on his journey to Mars. They start thinking about raising a family and that their kids will be martians. Sheldon likes that idea about having kids with neat Martian names.
In "The Skywalker Incursion", Amy obtains Howard's TARDIS at Bernadette's insistence and mounts it's door on her bedroom hoping to tempt Sheldon into her bed. They do play Doctor Who, but Sheldon runs in dressed as the Doctor and forgets something and runs back out. Amy tells herself that she should have thought this out better.
In "The Fortification Implementation", Amy and Sheldon finally spend the night together, though only as a sleepover in a fort that they built together. When their date night ended at ten o'clock, Sheldon was having such a good time that he wanted Amy to extend the parameters of date night. After negotiating a G-rated sleepover within the fort, Amy produced a sleepover kit complete with pajamas and toothbrush that she hid under a couch cushion two years previously.
In "The Commitment Determination", Sheldon and Amy are making out on the couch on their fifth anniversary while Sheldon also asks Amy about the new The Flash TV show. Amy stops him thinking that he should be concentrating more on her. Sheldon thinks he is since he truly wants to know her opinion about the show. For a couple of days, he doesn't hear from Amy. Calling her, Amy admits that she is totally exhausted physically and emotionally from being his girlfriend, so she wants to take a break and think about their relationship. Sheldon reluctantly agrees and doesn't know what to do with the engagement ring he had.
=====Season 9=====
In "The Matrimonial Momentum" Amy is leaving her apartment to go to Howard's house to watch Leonard and Penny's wedding when Sheldon shows up in the hallway, startling her, and explains that eleven hours is enough time to sort things out. Then Amy says that it is still not enough. Sheldon continuously gets worse, lingering outside the Howard's window until being let in by Bernadette; however, Sheldon continuously badgers Amy, until he finally goes too far by remarking that she should hurry up, given that the age of her eggs are slowly ticking away. That's the last straw for Amy, who angrily declares that she thanks Sheldon for making it easy for her, and they are officially broken up, officially ending their relationship.
In "The Separation Oscillation", Sheldon appears in front of Amy's apartment to return her belongings. She pulls out a scarf reminding them the time they went ice skating, then Penny's red bra put in there by Sheldon to make her jealous. After that, he records a new episode of "Fun with Flags" which alludes to their breakup. He also sends the link to Amy with a headline: "Watch. This will make you mad". Amy goes straight to his apartment and demands him to take it down. Sheldon thinks she still has feelings with him because she watched the video, then happily skips down the hall.
In "The 2003 Approximation", Sheldon asks Amy to become his roommate to replace Leonard who moved in with his wife. She declines; however, she does defend Sheldon when Bernadette calls him a weirdo. Amy still finds him brilliant and insightful.
In "The Perspiration Implementation", Amy gets asked out by both Stuart and Barry Kripke; however, she turns them both down. Sheldon is told by the guys that he should trying dating to help move on so he asks the first two women he sees in the sports bar. The blonde doesn't understand his geeky cultural references and the other is her grandmother. The third women reminds him of Emily and looks too much like a clown. Sheldon and Amy awkwardly meet on the stairs and exchange their dating stories. Amy is shocked when she learns that Sheldon is asking women out to help him move on. Sheldon then says goodbye leaving Amy shocked and hurt.
In "The Spock Resonance", Sheldon is interviewed by Adam Nimoy about a documentary on Mr. Spock. In the middle of the interview, he brings out the engagement ring he was about to give to Amy and that surprises everyone. Sheldon afterwards was angry because Penny told him that he had emotions about being broken up with Amy and he denied that. Then, he decided to go to Amy's to ask to marry him. He sees Amy kissing her date David Gibbs (guest-starring Stephen Merchant) and Sheldon leaves, devastated.
In "The Platonic Permutation", Sheldon and Amy become friends again and spend Thanksgiving at the aquarium. At end of it, Amy asks Sheldon if she can be his girlfriend again, but he gently declines, telling her he excels at many things, but getting over her isn't one of them, leaving Amy devastated.
In "The Earworm Reverberation", Sheldon has a song stuck in his head which is driving him crazy. He's also driving Leonard and Penny crazier than usual. Meanwhile, Amy decides to try another date with David Gibbs. After Sheldon realizes the significance of the song ("Darlin" by the Beach Boys), it's connection to his feelings for Amy and how she has softened him, he heads over to her apartment. Just as Amy and Dave are about to kiss, Sheldon knocks. Amy excuses herself and Dave gets excited about meeting him, then she tells Sheldon that it's not a good time. Sheldon doesn't care and tells her about the song and that he can't get her out of his head/heart and that he loves her. Amy tells him she loves him too. Dave excitedly tells them to kiss, which they do - a very passionate one! Dave excuses himself as he leaves and Shamy continues to kiss.
In "The Opening Night Excitation", Sheldon decides to skip the premiere of the new Star Wars movie so he can be with Amy on her birthday. Amy learns from the girls that he is planning on being physical with her. That night Sheldon is fine that she already knows. In her bedroom, she is nervous; however, Sheldon tells her that they'll figure it out together. Both enjoyed sex much more than they thought they would. Sheldon plans on doing it again on her birthday next year which is fine with Amy.
In "The Meemaw Materialization", during Meemaw's visit to Pasadena, Sheldon is reluctant to stand up for Amy in front of his beloved grandmother. He finally does though obviously at the urging of Penny. Amy learns about the engagement ring he got from his Meemaw. After getting over the shock she hints to Sheldon about when is she going to get it. Sheldon blows up and tells her to slow down since he has just given her his virginity.
In "The Valentino Submergence", Sheldon adds Amy's name to the "Fun with Flags" show as a Valentine's Day present and because she has become so much a part of his life. The live show falls apart since Raj and Kripke call in to advice on their love lives. Sheldon finally joins in and talks about the pain he had during his breakup with Amy. He feels because of it, their relationship is even stronger.
In "The Celebration Experimentation", Amy wants to throw Sheldon a birthday party because of the wonderful birthday he gave her. Sheldon agrees, but says that she owes him big. Helping Sheldon dress beforehand she tells him that he looks nice in his suit, but maybe later she can see him in his "birthday suit". Sheldon thinks that he is wearing his birthday suit. No sex tonight. When Amy toasts Sheldon she remarks that it is traditional that the birthday boy get the presents, but her greatest present ever was the day he was born. Also she and Leonard argue who should go talk to him after Sheldon runs into the bathroom. Penny goes to do it.
In "The Big Bear Precipitation", while spending the weekend in a cabin Sheldon and Amy are playing the drinking game "Never Would I Ever"... Sheldon never drank milk past the expiration date. Amy never cancelled a dentist appointment. Sheldon never put his foot in the ocean. Amy never honked just because she liked something. Sheldon never played or even touched a Frisbee. Amy never put salt on her food before at least tasting it. They both agreed on all these topics showing how much they are alike. Then Sheldon never pushed all the buttons in an elevator. Amy takes a drink with a devilish look on her face. Sheldon's jaw drops, scandalized. Amy then shrugs, puts her glass down and says, “Everyone has a past.”
=====Season 10=====
In "The Conjugal Conjecture", Sheldon stands up during Leonard and Penny's vow renewal to say something to someone very special. Amy mistakes it for a pending marriage proposal.
In "The Cohabitation Experimentation", they finally move in together as a part of a five-week experiment suggested by Amy after a plumbing accident renders her apartment uninhabitable. Sheldon wonders if any comfort he feels from living with Amy could be due to his normal surroundings so they move into a neutral territory - Penny's old apartment. Coitus will be off the table until they see how comfortable their living arrangements work out. After discussing which side of the bed they prefer, they settle in for the night and Amy finds that Sheldon has rough dreams and he pushes her out of the bed onto the floor. The next morning they argue about whether they should live together. Sheldon is upset that as a scientist that she should not want to continue with their experiment. The science argument obviously turns them on and they adjourn to their apartment to make out.
In "The Hot Tub Contamination", Shamy is trying to adjust to living together. Amy doesn't want to have her life controlled by a bathroom schedule. She also wants to share a toothbrush holder with him. Sheldon claims to want them to see others, but admits to Penny that because they have been bickering like his parents, he doesn't want to hurt her like his father did his mother. Sheldon learns to compromise, eliminates the bathroom schedule and asks Amy to share a toothbrush holder making Amy very happy and sending Penny to tears.
In "The Fetal Kick Catalyst", Sheldon first dismisses Amy's request to have company over to their apartment and then he surprises her by preparing a trial brunch and inviting Stuart, Bert from the geology department and Mrs. Petrescu. a Romanian who lives downstairs.
In "The Veracity Elasticity", Amy has been lying to Sheldon that her apartment has been ready for two weeks. Sheldon notices that Amy seems to be keeping something from him. Amy admits her lie after Sheldon learns about it through the rest of the gang. Sheldon forgives her and agrees to consider keep living with her. After reaching the hallway between the two apartments, Sheldon is puzzled whether to go into 4B to be with Amy or return to 4A comparing it to the classical problem Buridan's ass/Buridan's Donkey. Amy comes by wondering what he was doing, discusses Buridan with him and then goes into 4B. Sheldon so gets involved in the discussion that he follows Amy to live with her, perhaps permanently.
In "The Birthday Synchronicity", pregnant Bernadette has a false alarm trip to the hospital before she has her baby interrupting both Lenny and Shamy who are trying to have sex. It is Amy's birthday so it time for their annual coital activities. After they go to Harry Potter World, they come home to hove sex since Sheldon considers their earlier activities foreplay.
In "The Holiday Summation", Shamy visits Mary Cooper in Texas where Sheldon is reluctant to tell her that they are living together due to her religious beliefs. Sheldon is surprised that she couldn't be happier for them and also learns that his mother thought he would never find anyone. Sheldon goes off and rebels dressing like an idiot and getting an earring. Amy also learns that even though Mary likes her, she does think that Amy is weird.
In ”The Romance Recalibration”, Penny takes Amy on her spa weekend. Sheldon and Amy's farewell which starts in a make-out session and ends with them trying to top each other on how much each loves the other really bothers Penny who is questioning the romance in her marriage.
In "The Allowance Evaporation", Amy learns from Bert that Sheldon has told several people (Leonard, Howard, Raj, Kripke, and a cafeteria lunch lady) at the university that they only have coitus once a year. She is quite shocked to learn this news and almost chokes on her drink hearing it. Sheldon makes up a chart of Zones of Privacy and promises not to discuss initiate issues or bathroom practices with other people though by the end of the episode he does disclose publicly where Amy is in her menstrual cycle.
In "The Escape Hatch Identification", Sheldon calls Dr. Beverly Hofstadter for help since he is having trouble of accepting the fact that someone else is taking his room. Beverly says that Sheldon has insecurities about his relationship with Amy and needs his room as an escape hatch for their relationship. Amy retorts that their relationship is sound, but realizes his need for a backup plan.
In "The Collaboration Fluctuation", Sheldon and Amy begin working together on using the Copenhagen Interpretation for a neurobiology concept. Although it starts off with frequent rotations between respect and arguing, they still manage to make their partnership work even though they do their best work when they argue.
In "The Long Distance Dissonance", Ramona Nowitzki reappears hanging around Sheldon while Amy is away at Princeton University. The gang becomes worried for Sheldon when she begins chasing him again. Ramona eats with him, goes swimming with Sheldon and visits with the gang in apartment 4A. Sheldon asks her if she has a romantic interest in him, she then asks him "What if I do?" and kisses him. Sheldon is shocked and then immediately flies to New Jersey to propose to Amy.
=====Season 11=====
In "The Proposal Proposal", Amy is being proposed to by Sheldon who stops and takes a call from Leonard and Penny. Amy is confused when she learns that Dr. Ramona Nowitzki kissed Sheldon, but is excited when she learns that that caused Sheldon to realized that Amy was the only woman he wanted to kiss for the rest of his life. After ending his call, Amy accepts the proposal and they happily embrace. That night during dinner with Amy's colleagues, he as always wants to be the center of attention. Amy explains how rude he was and then using an Avenger analogy, he tells her that they are a couple and he will have be a cameo in her life sometimes. He flies back to Pasadena so that Amy can experience the pleasure of her work and the adulation of her colleagues.
In "The Relaxation Integration", Sheldon sends out 80 save the date announcements to cover all possible dates until he finds the perfect one not near a birthday or important date. Sheldon is experiencing a more relaxed personality while talking in his sleep. Amy assumes that is the stress of planning for their wedding to which Amy tells Sheldon to try and relax more which doesn't go well. Finally he tells Amy to make all the wedding arrangements.
In "The Confidence Erosion", they start out enthusiastically planning their wedding together. First they split up the various decisions randomly and then start to fight about each other's choices. Amy suggests that maybe they should just elope and Sheldon remarks that he is free the next day. They get their license at city hall. Amy is fine with no formal wedding, but when their names are called, Sheldon doesn't want to do it. He wants a first dance with his new wife and they go off hand-in-hand to plan the Shamy wedding; after Sheldon gets a permit for hazardous wastes as long as they are at city hall.
In “The Celebration Reverberation”, Sheldon plans a ”Little House on the Prairie” dinner to honor Amy's birthday making an authentic pioneer meal from scratch. Though excited about it, Amy doesn't find it very tasty and both of them end up with food poisoning. She is even less interested in having their annual birthday coitus the next day. Finally well, they attend Halley Wolowitz’s birthday party together. At Sheldon’s suggestion, they make use of the children’s bounce house and then plan to adjourn to one of their bedrooms to have their annual celebration.
In "The Separation Triangulation" and "The Novelization Correlation", Sheldon was trying to consider other people's feelings. In the first, Sheldon moved into his old room to work at night and not bother Amy which drove Leonard crazy because Sheldon was being considerate. Secondly, Amy had an invitation to appear on the new Professor Proton show which she didn't want to accept since it would bother Sheldon. He still let her do it, though Sheldon let out his frustration by yelling up on the roof.
In "The Comet Polarization" Sheldon is enthusiastic about Stuart's new assistant Denise and her knowledge of comic books. Jealous Amy goes down to the comic book store and demands that Denise educate her so that it looks like Amy is interested in comic books. When Sheldon returns to their apartment, Amy wants to discuss her new DC book, but Sheldon is too exhausted from talking about comic books thus ending Amy's project.
In "The Athenaeum Allocation", Sheldon and Amy began searching for their wedding venue and want it at the Caltech Athenaeum Club. They get the venue, but Kripke has selected the date they wanted. At the end of the episode, they were looking at possibly having their wedding at the Planetarium.
In "The Reclusive Potential", Amy has her bachelorette party with Penny and Bernadette. She originally doesn't like their idea of their party - tea and making quilts so they then decide to go to a bar and get drunk. Sheldon goes off to meet a scientist, Robert Wolcott, in a cabin in the middle of nowhere, and he says that this was not his bachelor party. He enjoys spending time in the cabin at first, but then realizes that he misses Amy...and his phone.
In "The Monetary Insufficiency", Amy and the girls go shopping for a wedding dress. Amy picks one that doesn't look too appealing, but Sheldon says she looks beautiful and she decides to keep the dress. Penny admits that it is not one she would choose, but she plans to be the best maid-of-honor for Amy's wedding.
In "The Bow Tie Asymmetry", Sheldon is excited about marrying Amy, but worried about how perfect his bow tie will look. Amy says that there is beauty in asymmetry. While getting ready for the ceremony, his mother says that even imperfections can make something perfect. These comments make Sheldon rethink his string theory calculations delaying the wedding while Sheldon and Amy work on inventing Super-Asymmetry. Leonard joins them causing Penny to go ballistic and get them moving. Howard had gotten Star Wars actor Mark Hamill to replace Star Trek actor Wil Wheaton to perform the ceremony. Both sets of vows bring Mark Hamill to tears and as Sheldon leads Amy down the aisle, they are somewhat embarrassed to be serenaded by Barry Kripke. They are happily married and are best friends.
=====Season 12=====
In "The Conjugal Configuration", the newlyweds wake up very happy together at their honeymoon hotel overlooking Legoland. Their next stop is New York City to see the two night Harry Potter play on Broadway and take a Nikola Tesla walking tour. Amy gets frustrated when Sheldon wants to schedule everything including their sex. Sheldon admits that he has problems with intimacy and that he schedules it so he will not forget. Amy finally says that he can, just don't tell her the schedule so that it seems like it's spontaneous. After she makes a comment about computers and random numbers, Sheldon gets turned on and drags her back to the hotel.
In "The Wedding Gift Wormhole, Leonard and Penny give them a crystal dagger that came from Howard and Bernadette who got it from Raj. They over-analyze what it is and go on a scavenger hunt ending up at the coffee shop where they first met. In the shop's lost and found they find a locket and a pair of sunglasses again over-analyzing their meaning thinking that Leonard and Penny have given them the most wonderful gift. Sheldon then scrambles their WiFi password so the Hofstadters can also have a great experience. Sheldon is also thinking about giving the crystal dagger to Raj for his wedding thus completing the cycle.
In "The Planetarium Collision", Sheldon wants Amy to have more time to work on their Super-Asymmetry project; however, Amy has her own work to do. Sheldon get President Siebert to assign someone else to her project which infuriates Amy. Not only is she mad at Sheldon, but one of her worse fears is to have herself lost in their marriage. Losing her projects is that nightmare come true.
In "The Paintball Scattering", President Siebert suggests that Amy do the interviews on their paper due to Sheldon's quirks. One of her interviews results in the article entitled “The Neurobiologist Who Revolutionized Physics” which really bothers Sheldon. It's not about him. She did talked him up, but that is how the article came out and she says that she didn't write the article title.
In "The Confirmation Polarization", Sheldon and Amy are contacted that two Fermi-Lab scientists had confirmed their Super-Asymmetry theory. Meeting with the two scientists they know nothing about their theory, only that others had told them they had accidentally proven the projected results of the theory. They were more interested in seeing "Ellen" taped. Later they stated that only three team members' names can be submitted to the Nobel committee and they want Amy dropped since she isn't a physicist. The university supports their people and will put in their own submission with just Sheldon and Amy as the discoverers. Amy is willing to drop out if it means her husband can fulfill his dream.
In "The Inspiration Deprivation", after Amy's outburst at the university reception Sheldon and Amy are hauled into Human Resources and told to keep their traps shut. Also Amy is told how much she will be an inspiration to women everywhere interested in science. Amy is very rattled about being an important role model. To calm down she and Sheldon spend an hour in a sensory deprivation tank. Sheldon is relaxed, but Amy has a nightmare about disappointing women everywhere. Finally she returns to Human Resources saying that she accepts the role, but also should not be silenced since she is capable to deliver the message.
In "The Plagiarism Schism", Barry Kripke who went to school with Greg Pemberton finds evidence that he plagiarized his doctorate thesis. Sheldon and Amy do not want to win by discrediting a colleague; however, Leonard does get the evidence from Kripke. The Coopers hand the evidence over to Greg Pemberton, which shocks his partner Kevin Campbell. They get into a fight and Dr. Campbell releases it on the Internet getting Greg Pemberton fired. Later Dr. Campbell wants to join Sheldon and Amy on their team, but is turned down.
In "The Change Constant", the Hofstadters and the Coopers are waiting for the Nobel Committee to call from Sweden. Kripke gives then a fake phone call calling them suckers. Amy then gets the call and quietly says that they won. Sheldon can't believe her so Leonard slaps him, they all shout excitedly and have a big hug together. Sheldon has a hard time dealing with the fame and attention from his colleagues and reporters. Then after Raj gives Amy a makeover, he runs off with Penny to The Cheesecake Factory cursed by all the changes. Penny reminds him how much he's changed in the last twelve years and that the fact of change is really the constant. Sheldon accepts that.
In "The Stockholm Syndrome", Leonard and Penny are keeping a secret that she is expecting. When Penny returned from drinking with Sheldon at The Cheesecake Factory, they hopped into bed without "wrapping" something. Penny seems happy, but is unsure about the whole baby thing. Sheldon and Amy pay for their friends' clothes, tickets and hotels so they can all attend the Nobel Prize ceremony. Sheldon thinks that Penny was quite sick on the plane, so the secret comes out and he is glad he won't get sick. Leonard is mad that Sheldon doesn't congratulate them and at the hotel, Sheldon shows no concern for Howard and Bernadette's fears for their kids. Amy calls Sheldon out on his selfishness and he eventually has a change of heart. Penny is very sick and claims that she has to be there for Amy. At the ceremony Sheldon puts aside his self-centered speech and realizes that his achievement isn't just his, but also his family and friends who encouraged him and tolerated him. Sheldon introduces his friends to the world and tells them how much he loves them. The series concludes with the married couple eating happily with their friends.
===Vanessa===
Sheldon tells Howard and Raj that as they were responsible for getting him and Amy together, he would like their help in finding a new girlfriend. Howard and Raj discuss putting Sheldon on dating websites again before deciding to set up a scavenger hunt type challenge where a woman has to successfully complete all the challenges and at the end would get Sheldon's contact information. The challenge would need to be completed by 10:00pm that night. They count down until 10:00 pm. No one arrives at the apartment. A moment later there is a knock at the door and it is a girl named Vanessa Bennett. They seem to get along well and she enjoyed the challenge' physics, flags and multi-languages, but since she didn't complete the challenge on time Sheldon thanks her and shuts the door in her face.
===Mrs. Fowler===
In "The Consummation Deviation", Sheldon first tries to bond with Larry Fowler who is more interested in Howard's magic tricks. He then stops in on his mother-in-law. At first they find nothing in common until they both bond over being angry at Amy. She had claimed that she and Sheldon couldn't visit because of Sheldon. He found her delightful which probably thrilled Amy.
==Family ==
Sheldon is very different from the rest of his family. His mother Mary Cooper is a devout Christian and a loving parent, and is one of the few people who refer to him as "Shelly". Everyone in the gang loves her. Leonard Hofstadter called her Sheldon's "Kryptonite" and will often call her when Sheldon is having serious issues.
In "The Mommy Observation", Sheldon surprises her mother with a visit and caught her have sexual relations with her boyfriend. First Sheldon condemns her for her coitus despite her Christian beliefs and she sends him to his room. Howard, who was in Houston lecturing at NASA, tells him how he drove away his mother's boyfriend and how she has been lonely ever since. Sheldon decides to not stand in his mother's way of happiness though he still chooses to condemn her internally. Also he tries to initiate a talk with her about the birds and the bees.
Sheldon also has a fraternal twin sister, Missy Cooper, a hostess at Fuddruckers at the time of the Pilot. Tall and attractive, she caught the attention of Leonard, as well as of Raj and Howard. Sheldon believes that within Missy's eggs lays the potential for another "superior mutation" like himself, and on this grounds considered his friends unsuitable to be with his sister. Sheldon became offended when he found that Missy tells others he is a rocket scientist; he apparently thinks the title is inaccurate and below him, telling her she might as well say he is a toll collector at the Golden Gate Bridge. Her next appearance was the Shamy wedding where she was pregnant and separated from her husband. Her son stayed at home with his father.
Along with Missy, Sheldon also has an older brother, named George Cooper Jr. who often beat him up, along with Missy. Mary described the two of them as being "dumb as soup." George Jr. was never shown on the show, until the penultimate Season 11 episode "The Sibling Realignment". He owns a the Dr. Tire Store. After Sheldon learns that his mother will not attend Sheldon and Amy's wedding unless he invites his brother, Sheldon goes to try and convince him, taking Leonard along. After Sheldon meets George again for the first time in a decade, things go a little problematic between them. Leonard talks with George, Sheldon is made to apologize to him since he never knew the truth or understood George's true motives. Sheldon apologizes and the two brothers make up, with George saying that he'll attend Sheldon's wedding. Leonard finds out that George took care of Sheldon the same way he did by driving him around, explaining his actions and helping him navigate the real world.
Sheldon's father, George, an almost-redneck Texan Homer Simpson, died in 1994, 13 years before the series began. Missy visited Sheldon to bring paperwork regarding their father's estate while visiting California. Sheldon recalls that his father would force him to watch football ever since he was four despite his lack of interest for the sport. He also taught him archery which gives Sheldon an odd smell of K-mart bourbon whenever he plays it, including the Wii version.
Sheldon is also very close to his maternal grandmother Constance, whom he calls "Meemaw," who in turn calls him "Moon Pie".
Sheldon also cherishes the memory of his Pop-Pop, Meemaw's husband, who was his only relative that urged him to follow his dream into science. His grandfather passed away before Christmas when Sheldon was five, which greatly traumatized him. When his Christmas wish to Santa to bring back Pop-Pop didn't come true, it soured him so much he hated the holiday altogether.
Sheldon has a maternal uncle, Edward, who is called "Stumpy" as the result of a time when he cleaned a wood chipper by hand. Sheldon had another uncle, called Carl, who was killed by a badger while cleaning a chimney. And another uncle that may have done things to children that were legal in Oklahoma per "The Clean Room Infiltration".
Sheldon has an uncle, Roger and a now-deceased Aunt Ruth. In "The Engagement Reaction", Sheldon mentions Ruth died in a hospital when she went there to visit Roger, she caught something, bit the dust a week later and the two of them now share a coffee can on Sheldon's mother's mantel.
== Relatives==
*Father: George Cooper Sr.
*Mother: Mary Cooper
*Brother: George Cooper Jr.
*Twin Sister: Missy Cooper
*Grandmother: Meemaw
*Grandfather: Pop-Pop
*Uncles: Carl, Edward, Uncle Roger; There's another uncle who gave children gifts like Santa and was not arrested in Oklahoma for his actions.
*Aunt: Aunt Ruth
*Former Sister-in-laws (via George Jr.): Unnamed
*Brother-in-law (via Missy): Unnamed
*Nephew (via Missy): Unnamed
*Nephew/Niece (via Missy): Unnamed/Unborn
==Eating habits==
Consistent with his characterization, Sheldon has many detailed and routine eating habits. His gifted memory allows him to remember that he stopped breast feeding on a drizzly Tuesday (S2E01). He loves to eat at Bob's Big Boy, an American restaurant chain, but eats at the Cheesecake Factory on Tuesday nights (presumably before the occasional Klingon Boggle, which replaced eating at Big Boy (which then moved to Thursday until they had pizza on that day. Now Sheldon most likely eats at Big Boy whenever or on special occasions.) 
*Breakfast: Sheldon always eats oatmeal for breakfast on Mondays, and always has French toast for breakfast on certain days. On Saturdays, it's cereal and Doctor Who.
*Burgers: Sheldon prefers burgers at Big Boy [S01E05], but later changed to the ones at the Cheesecake Factory. He prefers his burgers cooked medium-well, with dill slices not sweet, individual relish packets, and served with onion rings with extra breading. When ordering Cheesecake Factory burgers, he gets the barbecue bacon cheeseburger with barbecue sauce, bacon, and cheese on the side [S02E07].
*Cereal: Sheldon sorts his cereal numerically by fiber content, and rewards himself with "Honey Puffs" cereal [S01E02]. Cereal is eaten with 1/4 cup of 2% milk while watching Dr. Who on BBC America on Saturday mornings [S01E07].
*Chinese: Usually eaten on Friday nights [S02E02]. He prefers his chicken diced, not shredded with low sodium soy sauce and spicy hot mustard, also brown rice instead of white [S02E04]. Sheldon is adamant that the number of dumplings can be evenly split between all partakers of the meal, and always wants it from the restaurant Szechuan Palace. Sheldon even tries to learn Mandarin to confront the restaurant when he believes they have been passing off orange chicken as tangerine chicken.
*Cookies: Oreos are to be eaten with a glass of cold milk [S02E08].
*Desserts: per his mother, Sheldon's favorite dessert is cobbler [S01E04].
*Drinks: Sheldon drinks neither coffee nor alcohol, because he promised his mother that he wouldn't start doing drugs while he resided in California. Instead he likes drinking Diet Coke®. When forced to order a cocktail, Sheldon solves the problem by ordering a "virgin Cuba Libre," which is nothing more than a Coke® in a tall glass, served with a lime wedge. He then goes on to ask if Penny would make it diet. Sheldon drinks herbal tea, sometimes with honey. His favorite flavor appears to be chamomile. Sheldon drinks hot chocolate only in the months containing the letter "R" (January, February, March, April, September, October, November, December) explaining "What is life without whimsy!" Sheldon has also been seen drinking: 
**​orange soda [pilot episode]
**faux Monster energy drink [S01E03]
**apple juice [S01E06]
**faux Diet Coke [S01E08]
** faux Aquafina water [S01E09]
**faux V-8 juice [S01E12]
** warm milk when he can't sleep [S02E01]
**faux 7-Up [S02E02]
**faux Diet Sprite [S02E03]
**cold milk with cookies and faux Dasani bottled water [S02E08]
*Grilled Cheese: demanded by Sheldon when he had a cold; although he pointed out that his mother always made him split pea soup, with hot dogs cut up in it, and homemade croutons [S01E11].
*Movie Food: Popcorn, Red Vines, Slushy Sheldon doesn't like to go to the cinema if he can't eat Red Vines or drink Icees during the movie, and only if someone comes with him, so that he/she can give him the Heimlich Maneuver in case he chokes on popcorn. On the matter of Icees vs. Slurpees, Sheldon maintains that the two are completely different.
*Oatmeal: eaten for breakfast on Mondays [S03E03].
*Pizza: Sheldon eats Giacomo's pizza on Thursdays, with sausage, mushrooms, and light olives [S02E06]. In "The Agreement Dissection", however, Sheldon mentions that they used to order from a restaurant called Franconi's, which went out of business, forcing them to switch to Graziano's.
*Popcorn: all movie visits must include popcorn, which is why one should not go to the movies alone due to risk of choking [S02E02].
*Pudding: Sheldon prefers chocolate over tapioca [S02E13].
*Thai food: eaten on Mondays - Mee Krob with extra peanuts.
Sheldon does not believe that three-tined forks are, in actuality, forks, but tridents, and refuses to eat with them. He will therefore not eat in strange restaurants. Sheldon dislikes haggis and blood pudding. Sheldon is in the habit of reminding people that chili by definition does not have beans in it. Like Leonard, Sheldon hates Greek food, saying a lamb kebab is "little cubes of charred meat that tastes like sweat".
==Routines==
Sheldon has many routines which he follows strictly. His Saturday morning routine is to wake up at 6:15, pour himself a bowl of cereal, adds a 1/4 cup of 2% milk, sit down in his spot on the couch and turn on BBC America to watch Doctor Who. If he cannot complete this routine for some reason, he becomes very distraught. In addition, Sheldon goes to the Comic Book Store every Wednesday so that he can see all the new comics on New Comic Book Day. Also, every Wednesday night is "Halo Night", and Sheldon makes a big fuss about not starting at exactly 8:00 p.m. He must have the exact amount of time to play the game or else he takes the time out of eating or bathroom time. Sheldon does his laundry every Saturday night at 8.15 p.m. and uses a FlipFold to fold his t-shirts and socks. Each day, Sheldon has a specific pair of pajamas to wear. In the case of a stain, he still would not swap a pajama. He would rather sleep without bottoms as seen in "The Barbarian Sublimation", when he spilled grape juice on his bottoms. Sheldon hates it when people change the contrast of the TV settings, talk to him through the bathroom door, change Band-Aids in front of him, buy generic ketchup, forget to rinse the sink, adjust the thermostat, cook with Cilantro, or mock trains. It is revealed in "The Staircase Implementation" that, when there is an emergency in the apartment, Sheldon turns the apartment's flag upside down to indicate it.
==Technology preferences ==
Being a scientific genius, Sheldon is very particular about his technological devices. Early on in the series, he uses what seems to be a customized Dell XPS M1710. After being robbed, he adopts an Alienware M17x Nebula Red laptop that runs Windows 7, which he doesn't like as it is more user-friendly than Windows Vista. Sheldon's favorite Linux-based operating system is Ubuntu. Sheldon has an iPhone 4 and he and his friends enjoy making fun of Apple Genius Bar employees. He is also shown to use a Macbook Pro, with a red case, when video chatting with Amy Farrah Fowler.
=== Video games===
Sheldon and his friends play many video games, such as Age of Conan, where he is a conqueror by the name of "Sheldor the Conqueror" and has reached level 80. Sheldon and all of his friends play numerous multiplayer online games; he has a Night Elf rogue and later stated that he has a Blood Elf warlock in World of Warcraft, loves Super Mario Bros (wanting to control people in the same way he can control Mario in the video game Super Mario 64) and plays Halo every Wednesday night with his friends. He also plays bass guitar in the video game Rock Band. When Sheldon plays Wii Sports Archery, he likes to draw an imaginary arrow out of an imaginary quiver, because he believes "the people at Nintendo can only go so far in helping us recreate an actual athletic experience. We have to do our part, too." Sheldon is not good at Wii Mario Kart. Raj points out that, in real-life or in games, he cannot drive; however, Sheldon is very good at Wii Sports bowling (and bowling in real-life). Sheldon also likes to play the vintage text adventure game Zork.
== Trivia ==
*In the episode The Bachelor Party Corrosion, it is implied that Sheldon has strong feelings about NAFTA, a free trade agreement that came into force in 1994.
*Sheldon will end up being the character with the most appearances in the entire franchise by the time Young Sheldon ends unless another character gets a longer sequel.
*In "The Russian Rocket Reaction", Sheldon reveals he was 9 years old when he started his all-time enemies list on a 1989 floppy disk.
* His age is further constrained by the following consideration: Sheldon is a Taurus, according to "The Peanut Reaction", placing his birth date between April 19 and May 20 of 1980. This age is supported by Leonard's comment that Sheldon has been emotionally stuck for about 29 years in "The Einstein Approximation", with an air date of February 2010; however, a family chart in "The Cruciferous Vegetable Amplification" shows that he is 29 at the time of the episode, which aired in September 2010. Further, in "The Friendship Contraction", premiering in February 2012, Leonard described Sheldon as a "30-year-old man who can't survive on his own". (Though, it is possible Leonard was just being imprecise.) These latter two statements indicate a birth date between April 20 and May 21 of 1981 in the span of the Taurus. [Note that inconsistencies arise only if one assumes a temporal correspondence between the airdate of the referenced episode and the events featured in that episode. Therefore, Sheldon should be considered to have been born between April 19 &; May 20, 1980.]
*In The Celebration Experimentation and in A Rival Prodigy and Sir Isaac Neutron , Sheldon mentions to that he is born on 26th February 1980 making the Taurus theory false. 
**In real life, Jim Parsons, being nearly 7 years older, was the same age as the high school students Sheldon went to school with.
*Sheldon is 6 ft 1 in (1.85 m) tall – the height of Jim Parsons. (Parsons claims to measure 6 ft 2 in (1.88 m), presumably with shoes and the Sheldon life-size standup poster is 74 inches in height.)
*He weighs either 165 lbs (75 kg), as revealed in "The Porkchop Indeterminacy", or 140 lbs (63.5 kg), as estimated in "The Luminous Fish Effect"; however, those are most likely inaccurate now, due to the amount of time that's passed.
*He has been described as a "tall, thin... praying mantis" by both Penny and Amy Farrah Fowler.
*According to his mother, Mary Cooper, Sheldon has her eyes, his daddy's temper and "all that science stuff" comes from Jesus.
*Several ways to annoy Sheldon are laid out in "The Bad Fish Paradigm" (S02E01), including:
**Change the brightness/contrast settings of the television.
**Take a Band-aid off in front of him.
**Buy generic ketchup.
**Forget to rinse the sink.
**Talk to him through the bathroom door.
**Adjust the thermostat.
**Cook with cilantro leaves
**Pronounce the 't' in 'often'
**Make fun of Model trains/trains
*Mary's water broke for Sheldon and Missy in a Kmart, not a Walmart.
*Sheldon is rarely interested in sports, but is highly skilled at bowling and can consistently get strikes. ("The Wheaton Recurrence")
*Sheldon was raised in a Christian household in Galveston, East Texas, Texas, USA (Texas just happens to be the same state that Jim Parsons was actually born in), although he once said his mom had to help his dad during tornado season, as the aluminum house he had slipped off its cinder blocks. (This could have been his father's way of a tornado shelter or his parents divorced by then and he moved into an aluminum trailer. The reason for these explanations being as we saw Sheldon's childhood home in the season 3 premiere, where his mother still lives.)
*In the “The Excelsior Acquisition”, Sheldon states his belief that the universe we live in is deterministic but we still have free will.
*Sheldon has perfected "glow-in-the-dark fish"
*Sheldon has 212 friends on MySpace, even though he hasn't met one of them.
*Sheldon is allergic to bees and cats and gets asthma when he is around them (despite having a pet cat as a child and a whole glaring of cats when he missed Amy.)
*Sheldon considers himself to be the first "Homo novus" - a new, evolved species of Homo Sapiens.
**Homo Novus translates from Latin to "The New Man".
*Sheldon doesn't believe in luck or coincidence, instead citing the Law of Large Numbers (LLN) in statistics as the explanation for such phenomena.
* Sheldon hates going to the local Renaissance fair because he doesn't like the historical inaccuracies, such as Bavarian purity laws, mead flagons made of polypropylene, "ye olde" being put in front of everything, even modern underwear.
*Sheldon was humiliated on national radio during NPR's Science Friday with Ira Flatow when his voice became extremely high pitched due to helium seeping into his office as part of a prank by Barry Kripke.
*Sheldon agrees with the theory that 75-80% of any Rock-Paper-Scissors games you play with a person you are familiar with end up in a tie due to the limited number of outcomes and accordingly he prefers the variation Rock-paper-scissors-lizard-Spock/Rock-Paper-Scissors-Lizard-Spock.
*Sheldon used a Doppler Effect costume for Halloween.
*Sheldon uses his Green Lantern action figure as a safe place for his emergency money.
* Sheldon is fluent in Morse code.
*Sheldon believes that chocolate is the best flavor of pudding, trumping tapioca because of its high concentration of cyanide.
*Sheldon's favorite amino acid is Lysine, which is a major plot point to control the dinosaurs in the novel/movie Jurassic Park
*Sheldon thinks that his very strong attention to hygiene and his skill in writing Java Applets are the main reasons why his friends like him.
*Sheldon loves trains and monkeys.
*Sheldon contests that you can put a number to anything, including Rubik's cube stickers as well as friends.
*Sheldon fears dogs, dinosaurs, chickens and formerly birds.
*Sheldon had a cat named Lucky when he was a child, and this cat died because it was hit by a car. According to Leonard, this is another example of Sheldon's inability to understand irony.
**Sheldon thought about creating a griffin after Lucky was killed, but his parents didn't want to secure the appropriate eagle eggs and lion semen.
*Sheldon learned how to swim (on the floor) online. He went into the pool with Ramona Nowitzki in season 10.
**This appears, however, to contradict an episode of Young Sheldon in which he is forced to swim for P.E, though he barely succeeds.
* Sheldon cannot stand whistling. ("The Friendship Algorithm")
*Sheldon was very busy in his teenage years examining the range of diffusion in the super-symmetric theories, which brought him to re-examine the ultraviolet properties of Higher-dimensional supergravity a loop.
*Sheldon's expenses account for 46.9% of his after-tax income.
*According to Leonard, Sheldon doesn't like furniture made of reclaimed wood cause he believes the original owners will come back to take it.
*Sheldon imposes and teaches behavior lessons to any friend of his who disappoints him for three consecutive times.
*Sheldon thrives off his work and if left jobless he loses all focus and moves onto a new experiment/obsession every day, much to Leonard's dismay.
*Sheldon does not like teddy bears because he thinks bears are terrifying. He later told Amy that he does have one and that he often used it to wipe his nose.
*Sheldon was called by Leonard "one lab accident away from becoming a super villain".
*According to Leonard, Sheldon loves having his brain scanned.
*Sheldon only shows genuine affection for one person, his grandmother (or Meemaw), whom he writes too at least for most of the show.
*Sheldon is a Taurus, placing his birthday between April 21 and May 20, however, his birthday is apparently February 26, which makes him a Pisces, causing a continuity error. Though, it's possible that Penny guessed he was a Taurus.
*Sheldon, though unwilling to fight, is physically the strongest of the group, easily holding his own against Raj in an arm wrestle, and once referred to Leonard and Howard as 'tiny tiny men'. He was also able to move his entire dresser, with reasonable ease when barricading his door, due to paranoia, after being burgled.
*Sheldon owns a pocket watch. He bought it for himself when he was shopping for Amy to get her back in "The Shiny Trinket Maneuver". It is seen again in "The Locomotive Manipulation".
*Sheldon's little toes and lateral incisors are degenerated, which he says is due to his high level of evolution which keeps him from using a motor vehicle correctly.
*He says that he thinks that Erno Rubik, is a lonely guy.
*Sheldon once took a bet with Howard about a species of cricket, but lost and had to give Howard his rare Flash comic book.
*Sheldon went to a sci-fi convention on a bus for 10 hours and violated his personal rule of not urinating on buses twice to see Wil Wheaton, who didn't show up at the convention, which was revealed in season 5 that it was because Wheaton thought it be cooler to play on "Hollywood Squares". This and the events of the card tournament and bowling alley, led Sheldon to consider Wheaton his nemesis. He has made three websites dedicated to hating him: Willwheatonstinks.net, org and .com. It is unknown if Sheldon still has these websites after making up with Wil Wheaton.
*Sheldon has actually been kind to Penny; in two episodes he actually drove her to the hospital because she dislocated her shoulder after she slipped and fell in the shower and loaned her a significant amount of cash to help her in a financial pinch. The latter favor led Penny to think everyone was grilling her on her financial situation, even when they weren't.
*Sheldon was once offered a position at a secret military base but was later forced to deny the position due to his inability to keep secrets.
*Sheldon thought that the trip he and his friends took to the North Pole in Season 2/3 was "a hoot and a half."
* It was mentioned that Sheldon and Leonard once had (before they were robbed) "A TV, 2 laptops, 4 external hard drives, a PS2, PS3, Xbox, Xbox 360, a classic Nintendo, a Super Nintendo, a Nintendo 64, a Nintendo Wii, Halo 1-3, Call of Duty 1-3, Rock Band 1-2, Final Fantasy 1-9, Legend of Zelda, Legend of Zelda: Ocarina of Time, Legend of Zelda: Twilight Princess, Super Mario Bros, Super Mario Galaxy, Mario and Sonic at the Winter Olympics and Ms. Pac-Man. They also own Grand Theft Auto and Red Dead Redemption by Rockstar Games. They then probably got all the games and consoles again with a new T.V. and new computers. Sheldon's data was safe as well, as he was performing a backup in the previous episode. His new computer came with Windows 7 which he doesn't like cause it's much more user friendly than Windows Vista.
*Sheldon has adhesive whimsical duck stickers, holding umbrellas in his bathtub to prevent slipping.
* Sheldon keeps a daily log of social interactions called Sheldon's Log (in reference of Captain's Log).
*Sheldon doesn't trust banks because he believes that ATM machines will lead the charge of the robot armies when they revolt against humans.
*Sheldon keeps Band-Aids with him at all times, as well as in his kitchen, top desk drawer etc.
*As of "The Excelsior Acquisition" (S3E16), Sheldon has a restraining order from Stan Lee as well as the late Leonard Nimoy. In "The Vacation Solution" (S5E16), he also mentions having one from the late Carl Sagan. In "The Proton Displacement" (S7E07), he gets a new one from Bill Nye the Science Guy.
** Due to Sagan and Nimoy being deceased, it's possible that these restraining orders are null and void, unless they are also in effect for their final resting places.
*Sheldon doesn't seem to understand the concept of racism. This is implied in "The Egg Salad Equivalency" when he calls Mrs. Davis a slave to her sexual desires, even though she is black. In "The Tenure Turbulence", he also gives her the HBO series Roots, which is about the slave trade in America. 
** Though he does sometimes demonstrate a base understanding of the civil rights movement he does not understand, seemingly, its connection to racism.
*Sheldon has an in depth knowledge of American Football, only because he was raised in Texas and his father, a football coach, would force him to watch it from the time he was four until he went off to college — the longest seven years of Sheldon's life.
*Sheldon rarely laughs but when he does, it's a quick internal breath while showing a small smile. One of the rare times we hear him laugh properly is in season 5's "The Vacation Solution" over a physics Mad Lib. Another time, he has laughed like that is when Leonard made a multiplication error that was published.
*Sheldon has never worn a shirt with words, unless a shirt logo has words on it, like in episode 5 of season 4 and near always wears a long sleeved shirt under a t-shirt.
* Sheldon got drunk four times during the series: at the end of "The Grasshopper Experiment", "The Pants Alternative", "The Stag Convergence" and "The Habitation Configuration. In the last two, he showed a sense of humor and irony above what he normally has.
*Sheldon apparently believes in the possibility of time travel to the past according to the beginning of "The Luminous Fish Effect", explanations of time paradoxes in "The Nerdvana Annihilation" and a point of the room-mate agreement in "The Staircase Implementation".
* When somebody is distressed, Sheldon consoles them by saying "There, there", the only proof of his compassion towards other fellow human beings.
*Sheldon doesn't seem to like Internet memes, considering them "venality". He once gave Penny a "strike" (out of three and you're out) for sending him a picture of a cat who wants to "Haz cheezburger". He also put Leonard's e-mails in his spam folder over Leonard sending him a video of The Keyboard Cat.
*Sheldon is scared of waking Penny before 11 A.M., because she has an "I'll punch you in the throat" rule if he does.
* Sheldon is skilled in weaving as he is seen weaving ponchos in his apartment.
*If nothing is approved by Sheldon, he will not go through with it. (This is seen when Leonard, Raj, Howard, and Sheldon are trying to figure out the best way to see a movie. With Sheldon not approving any ideas, the others leave him. He responds: "They're right. It was the only option.")
*"Prevening" - Sheldon's made up word for the hours too late for afternoon, but too early for evening.
*Leonard had to surpass three barriers set by Sheldon in order to live with him in "The Staircase Implementation".
* Sheldon prefers the word "Hokum" over Bogus, Hocus Pocus, Mumbo Jumbo and Hokie Pokie.
* He considered Amy Farrah Fowler a friend, who is a girl, but not his girlfriend. This statement, however, is moot since "The Flaming Spittoon Acquisition" when the two officially become a couple.
* He missed getting Stan Lee to autograph his comic since he had to go to traffic court to pay a fine, but ended up in jail after he insulted the judge and refused to apologize. He then went to his house with Penny and ended up with a restraining order against him.
*Sheldon had built a robot called Shelbot, but was eventually discarded since Penny and Leonard were quite annoyed at Sheldon's idea for doing so.
*Sheldon owns a Flash costume which he has worn on three occasions: in "The Middle-Earth Paradigm" before Penny's Halloween party before switching to a Doppler Effect patterned suit, in "The Work Song Nanocluster" when high on caffeine and in "The Justice League Recombination" when attending a New Year's Eve costume party.
*Prior to Sheldon's date with Amy in "The Robotic Manipulation", the closest he had ever come to one was "a semi-incestuous Teens for Jesus Fourth of July Hoedown" at which he square-danced with his twin sister, Missy.
*Sheldon once attempted to declare his and Leonard's apartment a sovereign state and even made some currency for it. This was around the time Sheldon got fired from the university and he kept changing obsessions.
*Sheldon hates dirty socks. This is demonstrated by the time that Leonard, Raj, and Howard signed Sheldon up on a dating site and the site found Sheldon's perfect match, but Sheldon refused to go until Raj told him that he put a dirty sock in his apartment and would not remove it unless Sheldon went on the date.
* According to Sheldon in a deleted scene/blooper in "The Maternal Capacitance" the last time his mother visited, she tried to trick him into getting re-baptized below the Santa Monica Pier.
*Sheldon went to Johnson Elementary School until he went to college at age 11. It was there he earned the nickname, "Smelly Pooper" with kids going around saying, "Shelly Cooper is a Smelly Pooper". Amy believes this is gold for gossip.
*When Sheldon was under the influence of Howard's mom's Valium, he revealed that his mother used to smoke in the car. While "Jesus said it was OK", they couldn't tell their dad, George.
*Due to his good archery skills (taught to him by his father, George), Sheldon believes he would have made a great elf.
*There are two pieces of tape on the floor in Leonard and Sheldon's bathroom. One is in front of the sink and people must brush and floss their teeth from behind this piece of tape. A second piece is in front of the toilet "for those that stand up to pee", though what exactly it marks was not specified. If someone gets the mirror or floor dirty, before Sheldon's inspection, they can lose their T.V. privileges.
*As part of the roommate agreement created by Sheldon, Leonard has to wash his feet in a special tub before he gets in the tub or shower.
*The tentative title for his future autobiography is You're Welcome, Mankind.
*He had a Somalian pen pal who was kidnapped by pirates.
*Sheldon has to be knocked out by an anesthetic when he goes for a cleaning at the dentist, as he bites.
*In 1998, Sheldon bought a Tamagotchi, which is still "alive" as he puts it.
*Both Howard and Sheldon first connect with their girlfriends over the personalities of their mothers.
* In kindergarten, Sheldon recited Pi to a thousand places for the school talent show.
*In "The Bakersfield Expedition", Sheldon dressed as the Star Trek: The Next Generation character, Lt. Data.
*He might have aquaphobia (fear of water) per the episode "The Friendship Algorithm".
*Sheldon sometimes reverts to his Texan upbringing and uses expressions and ideas from his mother and father that are not as acceptable in the 21st century. (Women are like an egg salad sandwich...), (Swatting Amy on the behind and calling her a great gal.)
*As a child, Sheldon was not allowed to do his homework until after he watched football with his father.
*Sheldon can speak the Hawaiian language.
**Additionally Sheldon also knows Hindi.
*It's implied that Sheldon admires Madame Curie, as he put her in the collage for his screensaver along with Stephen Hawking and Amy.
*Sheldon meets James Earl Jones who likes Sheldon and he takes him out on a night on the town instead of having a restraining order issued against him as Leonard Nimoy, Carl Sagan, Stan Lee, and Bill Nye have done.
*In 2012, scientists at CERN actually DID find a new particle, and after additional research, confirmed that, in fact, the Higgs boson has been found such as Sheldon had been working on.
*Sheldon's abstinence from alcohol may have been an afterthought by the writers early on. In the pilot episode, when Leonard introduces Penny to the gang, he is seen drinking a beverage in a brown bottle with his dinner, which is presumably a beer.
* Another bad habit of Sheldon's is that he reveals himself bad events that he could have gotten away with, such as cleaning Penny's apartment at night, which Penny figured out that it was Sheldon by leaving a list for her closet, and a video message for Kripke after pranking him and inadvertently the university president and board of directors, something he could have easily gotten away with.
* Liev Schreiber - Prototype Sheldon? = He plays a scientist which has few people skills and is working on a weather model that leads him to find holes in time. Physics, time travel, alternate realities, all things that Sheldon is interested in. He looks like he could be Sheldon's brother and often had that squinty eye look while trying to figure out something or when his friends confused him. From the movie "Kate and Leopold".
** The life-model for Sheldon may have been found in the person of physics wunderkind Taylor Wilson, whose life and achievements are remarkably similar, right down to coming from much the same region of the US to the little matter of illegally stored yellowcake uranium used to fuel the working nuclear reactor in the garage - which Taylor built at age fourteen...
*Sheldon's sexuality remains largely a mystery for the first three seasons. It was presumed by most that Sheldon was asexual, which is a lack of sexual attraction to anyone. This is shown when Penny asks what Sheldon's "deal" is, (girls, guys, sock puppets?) In which Leonard responds that they have been operating under the assumption he has no "deal." When Penny insists everyone has a deal, Howard responds "not Sheldon." However, as his relationship with Amy Farrah Fowler develops it appears that Sheldon is perhaps demisexual, which is a largely unrecognized and rare sexual orientation, which is characterized by a lack of sexual attraction towards any person unless they become deeply emotionally or romantically connected with a specific person (Amy). Sheldon appears to feel at least a small amount of sexual attraction towards Amy (most notably in "The Locomotive Manipulation", season 7, episode 15)
*Sheldon is very fond of cats, having owned one as a child and having adopted several when his relationship with Amy temporarily ended. Although Sheldon has issues touching most people, places, things, and animals Sheldon appears to have no issues with touching cats, despite being allergic to them.
*Sheldon's IQ of 187 points places him in a very small fraction of a percent of the most intelligent people in the world. An IQ score is a normalized, scaled representation of the percentage of people that are at least as "intelligent" (as measured by the test) as the scored person. Current IQ tests are scaled to 15 points per one standard deviation (all IQ tests have 100 assigned to the population mean score), older tests (e.g. the popular Stanford-Binet Test) have 16 points per St. deviation. Assuming Sheldon's score is on a modern test, an IQ of 187 means a person with such an intelligence level occurs approximately once per 300 million individuals, i.e. Sheldon is in the top 25 smartest individuals on the planet (using 7.25 billion as the human population of the Earth). If his score were on a SD-16 test instead, he'd have a 1 in 37 million intelligence, and there would therefore be some 200 individuals as smart as or smarter than him in the world. 
**However, it's true that all IQ tests are highly imprecise for extreme values such as Sheldon's (owing to the very small number of people who can achieve such a result, rather than because of bad test design).
**An SD-15 test would assign an IQ of 195 to the smartest individual (i.e., the one with the best result) on the planet (and 194 to the next smartest); an SD-16 test would assign 201 or 202 to the smartest individual.
*Leonard and Sheldon are similar from The Odd Couple. Sheldon is similar to Felix: both are neat freaks and never let things go; difference is that Sheldon is incredibly arrogant and selfish sometimes than Felix.
*Sheldon has an engagement ring that he keeps in his drawer. This ring is revealed to be a maternal family heirloom that was temporarily lost when his Nana had her finger cut off by Comanches. After it was reclaimed, the ring was passed down from generation to generation, until Sheldon received it from his mother.
*Fun fact: there is a Cooper City in Texas, near Dallas/Fort Worth.
*In "The Pancake Batter Anomaly" (S1E11), Sheldon said at the age of 15, he got sick in Germany, and his mother had to fly back to Texas to help his dad at that time. This creates a continuity error in the episodes "The Thanksgiving Decoupling" (S7E9) and "The Proton Transmogrification" (S7E22) because Sheldon mentions to Bernadette's father Mike and to the ghost of Professor Proton, respectively, that his father died when he was 14.
*Sheldon, Leonard, Howard and Raj are the only characters of the current main cast who have appeared in every episode. Howard and Raj didn't appear in the "Unaired Pilot".
*Sheldon always has a habit of putting himself into Leonard's romances, either because he believes Leonard will do something to screw it up, he isn't very considerate of their [Leonard and the woman's] thoughts on it, or he simply does it for no good reason at all other than force of habit.
*Like Penny, Sheldon has/had commitment issues, but in his case, it's not/wasn't as severe, given that he took Amy's hand ("The Countdown Reflection"), initiated his first make out session with her ("The Locomotive Manipulation"), said "I Love You" before she could say it to him ("The Prom Equivalency"), planned on proposing to her ("The Commitment Determination"), and voluntarily decided on having coitus with her ("The Opening Night Excitation"). These examples also prove that despite Amy being ahead in the relationship, Sheldon is the one who takes all the major steps.
*The origin of his knock started after he found his father in bed with a strange woman. Afterwards, he always knocked three times to give people enough time to get their pants on.
*Sheldon Cooper born and raised in Texas and he doesn't have a Texas accent. He sounds more like Frasier Crane and sounds more like a Connecticut country club snob.
**Considering Sheldon's personality, it could be entirely possible that he did have one as a young child, then studied elocution to rid himself of it when he realized that it was, as southern comedian Jeff Foxworthy has joked, "not the world's most sophisticated accent."
* Sheldon has a lot of paychecks that he never deposited in a bank or even used in "The Excelsior Acquisition". Never explained why he didn't use his paychecks to pay his bills, his taxes and his insurance and mostly the rent. How did he stay in that apartment he didn't pay or have any utilities without his using his paychecks to deposit? Only one answer is Leonard, Leonard is the only one supporting him.
*Sheldon and Amy had sex once a year til they got married.
*Sheldon got his driver's license years prior to telling anyone but never drove cause he likes to be chauffeured around, believing it makes him feel important. Actually Sheldon got his driver's license in season 2, but never drove. The streets will be safer if he doesn't. Amy respects his wishes that she chauffeured around.
* Sheldon's right-handed and has the most screen time, surpassing even Leonard in the big bang theory.
*Sheldon skipped kindergarten though grade 1 might be the minimum required start.
*Sheldon loves trains.
*Sheldon's favorite type of cake is a 3 layered chocolate cake with strawberry frosting, as revealed in the episode "The Celebration Experimentation".
*His father used to give him archery lessons, by force though.
*He emails Penny his bathroom schedule once a week, even though Penny has clicked unsubscribe "like a thousand times", he still continues to do so.
*He considers Stuart to be his 9th favorite person, late in the show he's nicer to Howard than Stuart.
*He has a fear of nets.
*He used to have a fear of mailmen.
*He and his mother have an agreement that Sheldon would go to church at least once a year.
*He enjoys reading and collecting comic books.
* Comments over the series indicate that Sheldon's mother is Baptist, and possibly Evangelical, however Sheldon does not believe in or celebrate religion of any kind though.
**Sheldon's mother looks down on Catholicism shown in multiple episodes throughout the series, in one Big Bang Theory episode she visits a catholic church and makes a derogatory comment and in Young Sheldon when Tam says he's Catholic she says "Well that's too bad,".
*Sheldon's favorite Star Trek character is Spock.
*He doesn't drink coffee because before he left California he promised his mother that he would never do drugs, including coffee, however coffee isn't a drug.
*He drinks hot chocolate but only in months with an R in them, meaning he only drinks hot chocolate in January, February, March, April, September, October, November and December.
*His beverage of choice is moot.
*Sheldon claims that he has an Eidetic memory, which can sometimes "be a curse" as he was able to remember the lyrics to the song "We will rock you".
*Raj once used the little rubber part of Sheldon's tooth brush to pick food from his teeth and massage his gums.
*Sheldon's fake nickname, "Skippy Cavanaugh", is a reference to two things, one is from the Unaired Pilot, and the other, which might be a stretch, is from Nell Cavanaugh, Sheldon's class presidency rival during his high school times.
*He has to shave every 11 days.
*His favorite character in "The Simpsons" is Lisa Simpson.
*He has never touched Stuart.
*His testicles descended when he was 15.
* He has claustrophobia, a fear of small spaces.
*If his career in physics hadn't worked out, his original plan was to become either a professional ticket taker or a hobo, due to his love of trains.
*When Sheldon discovered that trains could prove Newton's first law, he felt like Neil Armstrong on the moon alone and happy.
*His favorite number is 73, he also has a purple shirt and a blue shirt, both with the number 73 on it in a white circle.
*Sheldon is a big fan of the Flash, as he has many Flash comics in his room, he has many Flash shirts, which he often wears, and he has a safety deposit box which he keeps comic books in some of the Flash, and was upset when he lost a bet to Howard and had to give one of his Flash comics to him.
*He owns nine pairs of pants and nine pairs of underwear.
*He doesn't take the bus when he is sick because he believes that when he pass out, he will wake up with his organs missing.
*He doesn't think that Geology is a real science, as he considers it to be "The Kardashian's of science."
*He wants 15 kids with Amy.
*His favorite color is blue.
*His favorite flavor of ice cream is vanilla.
*Sheldon has been shown to have a disliking towards swearing, however he sometimes swears.
*He and Amy have the same blood type.
*Sheldon can do the splits though he may have lost this ability since he was 9 years old when he displayed this talent.
*Sheldon has synesthesia as revealed in "The Sales Call Sublimation", when he indicates that to him, numbers and tastes can smell and look certain colors or things, such as the color pink and the smell of gasoline for twin prime numbers.
* Sheldon Cooper has a fear of living alone.
*Sheldon and Amy finally won the Nobel Prize in the finale, just hope it doesn't go to his head in the future.
*Sheldon finally thanked his friends and his family for helping him win the prize and helped him become a better person.
*Sheldon is the only one of the married men to not become a father or soon to be father by the end of the series; however, according to a brief comment made by Sheldon in the Young Sheldon Season 1 finale narration, the couple have children in the future.
**In Young Sheldon season 3 episode Body Glitter and a Mall Safety Kit, Sheldon narrates that he offered Amy a hot beverage in the middle of the delivery, confirming they have at least one child.
**They have a son named Leonard Cooper (originally Leonard Nimoy Cooper, which Sheldon wanted to name him), but Amy rejected it (Graduation). Amy let him name him Leonard after Leonard Hofstadter which was never confirmed.
**Sheldon usually forgets Leonard Nimoy has a restraining order on him.
*In Young Sheldon, it's revealed that Sheldon is ticklish.
*Sheldon can speak Spanish and Klingon.
==Gallery==
==Notes and references==
Category:Sheldon Cooper
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