Groundhog Day

Groundhog Day is a trope where a character (usually only one character) is caught in a time loop, doomed to repeat a period of time (often exactly one day) over and over, until something is corrected. The trope is named for the film Groundhog Day, which established the trope in popular culture.
It's a niche fanfic trope, but exists in many fandoms. Sometimes, it is a light/fluffy kind of work inspired by events from canon, other times it is a grueling and difficult experience for the characters. If the period of the time loop is within canon, the trope is often used to allow for a fix-it for a certain episode or scene in a series in order to explore how it could have gone different (and as fans prefer). Groundhog Day works typically focus on characters or relationships and their grow, given that, by nature of the premise, the plot events are rather predictable.
==Canon Examples==
=== Film ===
* Edge of Tomorrow
* Happy Death Day & its sequel, main character Tree Gelbman keeps repeating her birthday after she is murdered. It repeats until she kills her murderer.
=== Television ===
* Buffy the Vampire Slayer episode "Life Serial", Buffy Summers suffered a time-loop due to Jonathan Levinson putting a spell on her. Buffy has to assists customers at the Magic shop and must satisfy the customer; if she fails, the events reset to when the customer walks into the store.
* Legends of Tomorrow episode "Here I Go Again", Zari Tomaz replays the same hour on the Waverider which explodes at the end of an hour killing everyone on board. Zari repeats the hour, trying to figure out to stop the bomb and learning more about her teammates.
* The Melancholy of Haruhi Suzumiya, the "Endless Eight" arc sees the main cast relive summer vacation over and over. This continues until Haruhi, unknowingly the source of the loops, is satisfied with her summer vacation.
* Once Upon a Time, Storybrooke worked this way before Emma Swan arrived. Every day everyone did the exact same thing, with no one except Regina noticing.
* Puella Magi Madoka Magica episode 10 reveals that Akemi Homura has been repeating an unspecified number of time loops in order to save Kaname Madoka from dying.
* Russian Doll, the main character Nadia Vulvokov also has to keep repeating her birthday after she is murdered.
* Star Trek
* Supernatural episode "Mystery Spot", Sam Winchester replays the Tuesday Dean dies over and over.
* The X-Files episode "Monday", Mulder and Scully keep trying to foil a bank robbery, but the robber has explosives strapped to his body and always ends up killing them all. The only person who can see the loop is the robber's girlfriend.
=== Video Games ===
* In Stars and Time, Siffrin repeats the party's final dungeon crawl over and over again.
* I Was A Teenage Exocolonist, the main character relives their teenage years over and over due to a wormhole accident. Memories from past loops can be used to unlock new options and change events for the better in subsequent loops.
==Fanwork Examples==
The Avengers Movieverse: 
* What A Difference A Day Makes by goodboots, Gen, The Avengers pull a Groundhog Day. (2012)
* 10, 9, 8, car by pollyrepeat, Clint/Coulson, Clint was pretty sure he'd seen this movie. Like a lot of things since he'd joined the Avengers, it had been a lot funnier when it wasn't his life. (podfic by aphelant) (2012)
* Lokiday by Artemis_Day, Explicit, Set within The Avengers first film, a Loki/Jane fic where Loki and Jane are stuck repeated the same day together. "I'm sorry, Dr. Foster, it just doesn't make any sense. People don't fall in love after only knowing each other for one day!" "With all due respect, Agent Romanov, it's been a VERY long day." (2012)
* by theorytale, Loki/Tony Stark, It's seven a.m., Thursday fourteenth November, 2013. It always is. (2018)
* , a frostiron fic by STARSdidathing (2020)
* , a frostiron fic by melonbutterfly (2013)
Daredevil (TV Series):
* Rocky Horror Pancake Show by ChuckleVoodoos: Set in an Alternate Universe in which everyone gets a "glitch" once in their lives which allows them to repeat a certain day up to five times in order to make it better, and then continue to live in one of the realities. Foggy gets his glitch on the day of the Hell's Kitchen bombings, and sets out to save the city.
* When The Day Met The Night by goldstandard: This is your typical, average, Groundhog Day AU where Foggy has to re-live the day he discovers who the Devil of Hell's Kitchen really is.
Dracula:
* A time-loop fic is a small genre inspired by Dracula Daily, when fans compared going through the second and third DD runs with characters gone through time-loops, which led to many memes and some fanworks.
Harry Potter: 
* Getting the Hang of Thursdays by Hayseed, Snape/Hermione, A good day goes bad and then gets far worse than Severus could ever have imagined. Again and again and again. Inspired by the WIKTT Time-Loop Challenge.
* Tea and No Sympathy by who_la_hoop, a 70k Drarry fic with over 43k kudos on AO3, with translations into Italian, Russian, Chinese, French, Spanish and Korean.
* (honey) there is no right way, a Harry/Cedric fic which loops if Cedric dies in book 4
Hawaii Five-0:
*Ho'oponopono by ember_firedrake, Steve/Danny, Danny finds himself trapped in the same day over and over again.
The Hobbit:
* Hobbit Time Loops bookmark collection 
* Many Paths by flakedice Bilbo/Thorin - Bilbo wakes up in Dale. With the memory of a battle won but lives lost, he finds an army of Men and Elves readying to attack Erebor. Bilbo tries to save his dwarves. Again and again. 
* Round and Round Again by Antarctica_or_bust (various pairings) - Ori is cursed to relive their journey until the company succeeds; it takes a very long time.
* The World Spins Madly On by thedisgruntledone (Bilbo & Thorin) Caught in a cycle that centers on just a few months - those spent traveling with the Company of Thorin Oakenshield, Bilbo has to figure out how to stop time from resetting, and maybe, if he's very, very lucky, manage to change a few things for the better along the way.
Les Miserables:
* Toil Until the Old Colours Fade by drcalvin, a long Javert-focused, Javert/Jean Valjean work.
 
Merlin:
* Quickening Days by Fahye, Merlin/Arthur, In which dragons & ghosts & prejudices are confronted, Merlin wears a hat (twice) and a dress (once), Arthur breaks some crockery (lots), there are more pranks than pillowfights but at least one of each, and many secrets are revealed.
Mob Psycho 100:
* tomorrow isn't always another day by suitablyskippy (2016) – In which Mob and Reigen get stuck in a time loop but, Mob, characteristically, doesn't notice.
Multifandom: 
* Hourglass by Giandujakiss, a vid that mainly features SPN, SG1, Xena, Day Break, and many others that dealt with the trope.
* Infinite Loops series by MasterWeaver, an ao3 series which has fics for Long Live the Queen(game by Hanako Games), Skullgirls, Zombieland Saga, etc
One Direction: 
* Trade All My Tomorrows for Just One Yesterday by harriet_vane
Persona 5:
* Oh Alice, There's no Reflection in the Looking Glass. by intothefrisson
The Social Network:
* If I could take it all back then I would (But I won't) by salvadore - Eduardo wakes up and he's back in the Palo Alto house. Again. And again. Worst of all - he's not the only one who knows what's going on.
Supernatural:
* A general Meme on Tumblr generally appears on Tuesdays in light of the fact that it's the day Sam repeated hundreds of times. See the side gif for an example, for a few other examples, look here.
X-Men: First Class:
* Been There, Done That by AsYouWish - Erik Lehnsherr is stuck re-living the same day over and over again -- a day that just so happens to be the day he and Charles Xavier took a handful of mutants to Cuba to stop a war. podfic by litrapod
==Resources==
* Groundhog Day and Time Loop works at AO3
* Recs tagged Time Loops at Fancake
* "Groundhog Day" Loop at TV Tropes
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