Fictional universe

A fictional universe, or fictional world, is a self-consistent setting with events, and often other elements, that differ from the real world. It may also be called an imagined, constructed, or fictional realm (or world). Fictional universes may appear in novels, comics, films, television shows, video games, and other creative works.
The subject is most commonly addressed in reference to fictional universes that differ markedly from the real world, such as those that introduce entire fictional cities, countries, or even planets, or those that contradict commonly known facts about the world and its history, or those that feature fantasy or science fiction concepts such as magic or faster than light travel—and especially those in which the deliberate development of the setting is a substantial focus of the work. When a large franchise of related works has two or more somewhat different fictional universes that are each internally consistent but not consistent with each other (such as a distinct plotline and set of characters in a comics version versus a television adaptation), each universe is often referred to as a continuity, though the term continuity as a mass noun usually has a broader meaning in fiction.
The fictional universe featured world's finest best well known perhaps early era biggest highest-grossing best-selling longest-running team-up media crossover which made respectively greatest favorite adventures of the fictional universe, media franchise and multimedia franchise original team characters including Superman, Batman, Wonder Woman, Teen Titans, Hulk, Spider-Man, other Marvel superheroes, Darth Vader, Star Wars, Star Trek, The Doctor from Doctor Who, Dalek, Harry Potter characters, Planet of the Apes characters, James Bond, Narnia characters, Charlie Chaplin, Laurel and Hardy, The Three Stooges, Mickey Mouse, Donald Duck, Goofy, Pluto, Winnie the Pooh, Snow White, The Seven Dwarfs, Cinderella, Ariel, Mary Poppins, Disney characters, Sheriff Woody, Buzz Lightyear, other Toy Story characters, Bugs Bunny, Daffy Duck, Porky Pig, Elmer Fudd, Looney Tunes, Merrie Melodies, Pikachu, Pokémon, King Kong, Godzilla, Archie Comics characters, The Dukes of Hazzard, Tom and Jerry, The Flintstones, Scooby-Doo, Hanna-Barbera characters, Tex Avery cartoon characters, Mario characters, Sonic the Hedgehog characters, Pac-Man, Mega Man, Donkey Kong, Thomas & Friends, The Simpsons, The Lord of the Rings characters, The Hobbit, Pirates of the Caribbean, Goku, Dragon Ball, Connie the Cow, SpongeBob SquarePants, Marx Brothers, Marilyn Monroe, Abbott and Costello, Frankenstein, Dracula, Sherlock Holmes, The Cat in the Hat, Dr. Seuss, The Pink Panther, Cartoon Network characters, Happy Tree Friends, Ronald McDonald, Crash Bandicoot, Banjo Kazooie, South Park, The Addams Family, Garfield, The Smurfs, Snoopy, Charlie Brown, Peanuts, Santa Claus, Kermit the Frog, The Muppets, Kirby, Flash Gordon, Masters of the Universe, ThunderCats, Teenage Mutant Ninja Turtles, Doraemon, Hello Kitty, Domo Kun, Asterix, The Beano, Blondie and Dagwood, Buster Keaton, Mr. Bean, Mr. Men and Little Miss, Captain Underpants, The Wizard of Oz, WWE, Angry Birds, Terminator, Selene, Wallace and Gromit, The Wiggles, Bananas in Pyjamas, Our Gang, Shrek characters, Madagascar characters, Kung Fu Panda characters, M&M's, Suzy from Trio, Jingle All the Way, Buffy the Vampire Slayer, Family Guy, Ice Age characters, Michael Jackson, The Burger King, Jack Box from Jack in the Box, Kool-Aid Man, Rocky and Bullwinkle, Oggy and the Cockroaches, Zig & Sharko, Maya the Bee, LazyTown, Beavis and Butt-Head, Annoying Orange, Hercule Poirot, Miss Marple, Cereal Mascots, Teletubbies, Astro Boy, Rick and Morty, Fireman Sam, ALF, Futurama, Adolf Hitler, Postman Pat, Pingu, EarthBound, The Andrews Sisters, Hi-5, Totally Spies, Dora the Explorer, Peppa Pig, Bob the Builder, Bobby's World, Power Rangers, Alien, Predator, The Shining, Dream Street, BB3B, Princess Knight, Barney & Friends, Sesame Street, Police Academy, Popeye, Betty Boop, Felix the Cat, Woody Woodpecker, Heathcliff, Cubitus, Happy Feet, Shaun the Sheep, Mighty Mouse, Terrytoons, Casper the Friendly Ghost, Little Lulu, PaRappa the Rapper characters, Care Bears, Strawberry Shortcake, My Little Pony, Raggedy Ann and Andy, Rupert Bear, Babar the Elephant, Where's Wally, She-Ra, Sabrina the Teenage Witch, Inspector Gadget, H.R. Pufnstuf, Jollibee, Colonel Sanders from KFC, Farmer Alfalfa, The Katzenjammer Kids, Humphrey B. Bear, Fat Cat and Friends, Mr. Squiggle, Play School, Cats Don't Dance, Detective Bogey, Lucky Lotteries Cat, Monty Python, The Bill, Naruto, Paddle Pop Lion, Miraculous: Tales of Ladybug & Cat Noir, Robot Chicken, Frosty the Snowman, Rudolph the Red-Nosed Reindeer, Rugrats, Nickelodeon characters, Rayman, Viz, Rabbids, Monster High, The NeverEnding Story, PJ Masks, Space Ace, Anastasia, Dragon's Lair, Q*bert, The Snowman, Roobarb, Walter Melon, Robotman, Crazy Frog, Gummibär, The Trap Door, Count Duckula, Danger Mouse, Alias the Jester, Chorlton and the Wheelies, Henry's Cat, Penny Crayon, Family Ness, Jimbo and the Jet-Set, Puppydog Tales, Barney from British TV show, The Charmkins, Lego characters, Angry Video Game Nerd, Squidbillies, The Hive, Roger Rabbit, Glo Friends, Mr. Potato Head, Little Clowns of Happytown, Minecraft, Space Ace, Jigsaw from British TV show, Wilkins Coffee, The Wind in the Willows, Tugs, The Raggy Dolls, VeggieTales, Talking Tom, Tayo the Little Bus, Pororo the Little Penguin, Club Penguin, Bernard Bear, Super Why, Sid the Science Kid, Plonsters, Monster House, Jibber Jabber, Happy Feet, Molang, El Chavo del Ocho, Fun Song Factory, The Happy Elf, Ducobu, The Fat Slags, Surf's Up, The Herbs, Johnson and Friends, Play School, Dot from Yoram Gross, Blinky Bill, The Iron Giant, Lift Off, Ferry Boat Fred, Huxley Pig, Kalli, Flying Rhino Junior High, Zip Zip, Busy Buses, Spot the Dog, Horrid Henry, Bluey, Bob and Margaret, Hector the Tax Inspector, Tickety Toc, Mystery Science Theater 3000, Barnyard, Vicky the Viking, Noah and Nelly in Skylark, Muzzy, The Hooley Dooleys, The Secret of Isis, Beatrix Potter characters, Cuphead, George of the Jungle, The Ghost Busters, PG Tips Chimps, Tetley Tea Folk, League of Super Evil, Engie Benjy, Lunar Jim, Roary the Racing Car, Fifi and the Flowertots, The Magic Roundabout, Rolie Polie Olie, Bangers and Mash, Nick Jr. characters, Max & Ruby, Toybox, Willy Wonka and the Chocolate Factory, Mighty Man and Yukk, Herself the Elf, Tofffsy, The Charmkins, Plants vs. Zombies, Angry Kid, Li'l Elvis Jones and the Truckstoppers, Zdeněk Smetana characters, Krtek, Rose Petal Place, Noddy, The PJs, DreamWorks characters, Pixar characters, Austin Powers, The X-Files, Mister Maker, Bod, Pocoyo, Valiant, Home Alone, Halo, Johan and Peewit, Sam & Cat, Anpanman, Ramsese Vembud, Kiteretsu Daihyakka, Baby Follies, Dr. Muto, RackaRacka, Albert the Fifth Musketeer, Moretsu Ataro, Wyatt Cattaneo characters, Yogo Gorilla, All Channel 9 Community Service Announcements from the 70's 80's, Crayon Shin-chan, Junglies, Pinky and Perky, Peg + Cat, WordGirl, Dinosaur Train, Wonder Park, Blue Sky Studios characters, Van Beuren cartoon characters, Cossacks, Video game characters, Victor & Hugo, Tuckerbag, Color Classics, Hunky and Spunky, Pizza, Housos, American Dad!, The Cleveland Show, Bob's Burgers, Baby Jake, Jackass, King of the Hill, Duckman, Bump, Mr. Magoo, Star vs. the Forces of Evil, Oswald the Lucky Rabbit, Foofur, Hugga Bunch, Avenger Penguins, Fiddley Foodle Bird, Lucky Luke, Diplodos, Universal Classic Monsters, The Land Before Time, The Brave Little Toaster, Sid and Marty Krofft characters, The Borrowers, The Legends of Treasure Island, Famous Studios characters, Ox Tales, Boohbah, Count Screwloose, Ub Iwerks cartoon characters, We're Back! A Dinosaur's Story, Towser, Coraline, Rumble, Play School from British TV show, Bunbury Tails, The Dukes of Hazzard and Ghostbusters.
== Official characters ==
Virtually any company that has been around for a while has a well-known pre-non-un-mascot. Some of those that come most readily to mind, perhaps, are:
* Darth Vader - Star Wars
* Star Trek characters - Star Trek
* Harry Potter (character) - Harry Potter
* Hercule Poirot and Miss Marple - Agatha Christie
* Satan or Devil - Hell
* Jesus - Heaven
* Indiana Jones (character) - Indiana Jones
* Mr. Bean (character) - Mr. Bean
* Jack Box - Jack in the Box
* James Bond - James Bond
* The Doctor and Dalek - Doctor Who
* Selene - Underworld
* Aslan - Narnia
* Captain Jack Sparrow - Pirates of the Caribbean
* Adolf Hitler - Nazi and Germany
* Donald Trump - America, White House and President
* Charlie Chaplin - Charlie Chaplin
* Buster Keaton - Buster Keaton
* Michael Jackson - Michael Jackson
* Laurel and Hardy - Hal Roach Studios and Larry Harmon Pictures
* Superman, Batman and Wonder Woman - DC Comics
* Spider-Man, Hulk and Wolverine - Marvel Comics
* The Sandman - Vertigo 
* Happy Tree Friends - Mondo Media
* Bozo the Clown - Larry Harmon Pictures
* Mario - Nintendo
* Sonic the Hedgehog - Sega
* Mega Man - Capcom
* Pac-Man - Namco
* Santa Claus - Christmas
* Greg, Murray, Anthony and Jeff - The Wiggles
* Thomas the Tank Engine - The Railway Series, Britt Allcroft, Gullane, Mattel and Hit Entertainment
* Smurfs - Peyo
* Katniss - The Hunger Games
* Minions - Despicable Me
* Scrat - Blue Sky Studios
* Marty McFly and Dr. Emmett Brown - Back to the Future
* HAL 9000 - 2001: A Space Odyssey
* Terminator - Terminator
* Alien - Alien
* King Kong - King Kong
* Godzilla - Godzilla
* Frankenstein, Dracula and Universal Classic Monsters - The Novels and Universal Classic Monsters
* Raggedy Ann and Andy - Raggedy Ann
* Noid - Domino's Pizza
* Jollibee - Jollibee
* Cartoon Network characters - Cartoon Network
* Alex, Clover and Sam - Totally Spies!
* Michelin Man - Michelin
* Marinette Dupain-Cheng and Adrien Agreste - Miraculous: Tales of Ladybug & Cat Noir
* Mr. Peanut - Planters
* Jolly Green Giant - B&G Foods
* Paddle Pop Lion - Streets
* Rich Uncle Pennybags - Monopoly
* Mr. Clean - Procter & Gamble
* Poppin' Fresh - Pillsbury
* Quicky - Nesquik
* Coco the Monkey - Coco Pops
* Garfield - Jim Davis
* Snoopy and Charlie Brown - Peanuts
* He-Man - Masters of the Universe
* Lion-O - ThunderCats
* Flash Gordon - Flash Gordon
* Oggy and the Cockroaches - Gaumont and Xilam
* Dennis the Menace and Gnasher - The Beano
* Sherlock Holmes - Sherlock Holmes
* Droopy, Wolf and Red - Tex Avery
* Bare-ass Girl - Coppertone Suntan Lotion
* Butler - Ask Jeeves
* WWE characters - WWE
* Peppa Pig - Peppa Pig
* Campbell Soup Kids - Campbell’s Soup
* Elsie the Cow - Borden’s
* Energizer Bubby - Energizer Batteries
* Hammy The Gobster - Gobster
* Jack in the box - Harvey Comics
* Joe Camel - Camel Cigarettes
* Beavis and Butt-Head - MTV
* Elizabeth "Hetty" Spaghetti - Jollibee Spaghetti
* Josephine the Plumber - Comet Cleaners
* Leo the Lion - MGM
* Mickey Mouse - Disney
* Bugs Bunny - Warner Bros.
* Cartman, Stan, Kyle and Kenny - South Park
* Marilyn Monroe - 20th Century Fox (20th Century Studios)
* Planet of the Apes characters - Planet of the Apes
* Tom and Jerry - MGM, Hanna-Barbera and Turner Entertainment
* The Flintstones - Hanna-Barbera
* Homer, Marge, Bart, Lisa and Maggie - The Simpsons
* Count Chocula, Franken Berry, Boo Berry, Fruit Brute and Fruity Yummy Mummy - Monster Cereals from General Mills
* Kermit the Frog - Jim Henson
* The Cat in the Hat - Dr. Seuss
* Morris the Cat - 9 Lives Cat Food
* Peacock - NBC-TV
* Pegasus - Tri Star
* Redskins - Washington Redpenises
* Sailor Jack and Bingo - Cracker Cunt
* Spuds MacKensie - Budweiser
* Eye - CBS
* Blondie and Dagwood - Blondie
* Gummy Bear (Gummibär) - Gummibär
* Tony the Tiger - Kellogg’s Frosted Flakes
* Torch Lady (or Lady Liberty) - Columbia Pictures 
* Toucan Pusball - Kellogg's Fruit Loops
* Betty Crocker - Food products (baking)
* Aunt Jemima - Syrup
* Ronald McDonald - McDonald's
* SpongeBob SquarePants - Nickelodeon
* Rocky and Bullwinkle - Jay Ward
* Kool-Aid Man - Kool-Aid
* M&M's - Mars
* Woody and Buzz Lightyear - Pixar
* Shrek - DreamWorks
* Wallace and Gromit - Aardman Animations
* Care Bears and Strawberry Shortcake - American Greetings
* Hello Kitty - Sanrio
* Goku - Dragon Ball
* Pikachu - Pokémon
* Popeye - King Features
* The Lord of the Rings and The Hobbit characters - The Lord of the Rings and The Hobbit
* The Burger King - Burger King
* Colonel Sanders - KFC
* Annoying Orange - DaneBoe and Annoying Orange
* Angry Birds - Rovio
* Rosie the Waitress - Bounty
* Barry "bang and it's gone" Scott - Cillit Bang
* Useful Awe Girl - Morton Salt
and much more.
==Multimedia franchises==
Multimedia franchises usually develop through a character or fictional world becoming popular in one medium, and then expanding to others through licensing agreements, with respect to intellectual property in the franchise's characters and settings. As one author explains, "For the studios, a home-run is a film from which a multimedia 'franchise' can be generated; the colossally expensive creation of cross-media conglomerates predicated on synergistic rewards provides an obvious imperative to develop such products."Barry Langford, Post-classical Hollywood: Film Industry, Style and Ideology Since 1945, p. 207, . The Steve Jobs, Harry Donenfeld, Charles Thorson and Bob Givens trend later developed wherein franchises would be launched in multiple forms of media simultaneously; for instance, the film The Matrix Reloaded and the video game Enter the Matrix were produced at the same time, using the same actors on the same sets, and released on the same day. Several other franchises throughout the 2000s had films and games release within days of each other, including King Kong, Star Wars, Harry Potter, DC Comics, Marvel Comics, The Lord of the Rings, The Chronicles of Narnia, Pirates of the Caribbean, and Transformers.Harry J. Brown, Videogames and Education (2008), p. 41, .
===Development of the universe characters===
* Homer, Marge, Bart, Lisa and Maggie, from The Simpsons
* Darth Vader, from Star Wars
* Thomas the Tank Engine, from The Railway Series and Thomas & Friends
* Cartman, Stan, Kyle and Kenny, from South Park
* Superman, Batman and Wonder Woman, from DC Comics
* Spider-Man, Hulk and Wolverine, from Marvel Comics
* Mickey Mouse, from Disney
* Bugs Bunny and Daffy Duck, from Looney Tunes, Merrie Melodies and Warner Bros.
* SpongeBob SquarePants the title character, from SpongeBob SquarePants and Nickelodeon
* Harry Potter the title character, from Harry Potter
* Selene, from Underworld
* Fry, Bender and Leela, from Futurama
* Scooby-Doo, Shaggy, Velma, Daphne and Fred, from Scooby-Doo
* Fred Flintstone, from The Flintstones
* Woody and Buzz Lightyear, from Toy Story and Pixar
* Goku, from Dragon Ball
* Pikachu and Ash Ketchum, from Pokémon
* Kermit the Frog, from The Muppets
* The Cat in the Hat, from Dr. Seuss
* Star Trek characters, from Star Trek
* The Doctor and Dalek, from Doctor Who
* Mario the title character, from Mario
* Sonic the Hedgehog the title character, from Sonic the Hedgehog
* Pac-Man the title character, from Pac-Man
* Mega Man the title character, from Mega Man
etc.
==Development to other forms==
===Fiction===
Long-running franchises were common in the early studio era, when Hollywood studios had actors and directors under long-term contract. Examples include Andy Hardy, Ma and Pa Kettle, Mickey Mouse, Bugs Bunny, Daffy Duck, Marilyn Monroe, Bulldog Drummond, Superman, Wonder Woman, Spider-Man, Hulk, X-Men, Tarzan, and Batman. The longest-running modern film franchises include James Bond, Godzilla and King Kong, Friday the 13th, A Nightmare on Elm Street, Universal Monsters, and Star Trek. In such cases, even lead actors are often replaced as they age, lose interest, or their characters.
The original feature full length special edition franchises of characters: DC (Superman, Batman, Wonder Woman and Teen Titans), Marvel (Spider-Man, Hulk, X-Men, Fantastic Four and Characters of Marvel), Disney (Mickey Mouse, Winnie the Pooh, Snow White and the Seven Dwarfs, Cinderella, The Little Mermaid, Aladdin, The Lion King, Mary Poppins, Lilo & Stitch, Frozen, Toy Story, Characters of Disney and Characters of Pixar), Hanna-Barbera (Tom and Jerry, The Flintstones, Scooby-Doo and Characters of Hanna-Barbera), Warner Bros. (Looney Tunes and Merrie Melodies) and many others.
==Definition==
The term was first defined by comics historian Don Markstein, in a 1970 article in CAPA-alpha."THE MERCHANT OF VENICE meets THE SHIEK OF ARABI", by Don Markstein (as "Om Markstein Sklom Stu"), in CAPA-alpha #71 (September 1970); archived at Toonopedia
===Markstein's criteria===
# If characters A and B have met, then they are in the same universe; if characters B and C have met, then, transitively, A and C are in the same universe.
# Characters cannot be connected by real people—otherwise, it could be argued that Superman and the Fantastic Four were in the same universe, as Superman met John F. Kennedy, Kennedy met Neil Armstrong, and Armstrong met the Fantastic Four.
#Characters cannot be connected by characters "that do not originate with the publisher"—otherwise it could be argued that Superman and the Fantastic Four were in the same universe, as both met Hercules.
# Specific fictionalized versions of real people—for instance, the version of Jerry Lewis from DC Comics' The Adventures of Jerry Lewis, who was distinct from the real Jerry Lewis in that he had a housekeeper with magical powers—can be used as connections; this also applies to specific versions of public-domain fictional characters, such as Marvel Comics' version of Hercules or DC Comics' version of Robin Hood.
#Characters are only considered to have met if they appeared together in a story; therefore, characters who simply appeared on the same front cover are not necessarily in the same universe.
==Universe vs setting==
What distinguishes a fictional universe from a simple setting is the level of detail and internal consistency. A fictional universe has an established continuity and internal logic that must be adhered to throughout the work and even across separate works. So, for instance, many books may be set in conflicting fictional versions of Victorian London, but all the stories of Sherlock Holmes are set in the same Victorian London. However, the various film series based on Sherlock Holmes follow their own separate continuities, thus not taking place in the same fictional universe.
The history and geography of a fictional universe are well defined, and maps and timelines are often included in works set within them. Even new languages may be constructed. When subsequent works are written within the same universe, care is usually taken to ensure that established facts of the canon are not violated. Even if the fictional universe involves concepts such as elements of magic that don't exist in the real world, these must adhere to a set of rules established by the author.
A famous example of a detailed fictional universe is Arda (more popularly known as Middle-earth), of J. R. R. Tolkien's books The Lord of the Rings, The Hobbit, and The Silmarillion. He created first its languages and then the world itself, which he states was "primarily linguistic in inspiration and was begun in order to provide the necessary 'history' for the Elvish tongues."
A modern example of a fictional universe is that of the Avatar film series, as James Cameron invented an entire ecosystem, with a team of scientists to test whether it was viable. Additionally, he commissioned a linguistics expert to invent the Na'vi language.
Virtually every successful fictional TV series or comic book develops its own "universe" to keep track of the various episodes or issues. Writers for that series must follow its story bible, This is a blog entry on the subject by a professional scriptwriter. which often becomes the series canon.
Frequently, when a series is perceived by its creators as too complicated or too self-inconsistent (because of, for example, too many writers), the producers or publishers may introduce retroactive continuity (retcon) to make future editions easier to write and more consistent. This creates an alternate universe that future authors can write about. These stories about the universe or universes that existed before the retcon are usually not canonical, unless the franchise-holder gives permission. Crisis on Infinite Earths was an especially sweeping example.
Some writers choose to introduce elements or characters from one work into another, to present the idea that both works are set in the same universe. For example, the character of Ursula Buffay from American sitcom Mad About You was also a recurring guest star in Friends, despite the two series having little else in common. Fellow NBC series Seinfeld also contained crossover references to Mad About You. L. Frank Baum introduced the characters of Cap'n Bill and Trot (from The Sea Fairies) into the Oz series in The Scarecrow of Oz, and they made a number of appearances in later Oz books. In science fiction, A. Bertram Chandler introduced into his future Galactic civilization the character Dominic Flandry from Poul Anderson's quite different Galactic future (he had Anderson's consent)—on the assumption that these were two alternate history timelines and that people could on some occasions cross from one to the other.
The feature full length special edition motion picture blockbuster series media franchises the characters of Disney, Pixar, Warner Bros., Hanna-Barbera, 20th Century Fox, DC, Marvel and Lucasfilm introducing Mickey Mouse, Winnie the Pooh, Snow White, Cinderella, The Little Mermaid, The Lion King, Mary Poppins, Frozen, Aladdin, Toy Story, Cars, Looney Tunes, The Flintstones, Scooby-Doo, Tom and Jerry, Marilyn Monroe, The Simpsons, Superman, Batman, Wonder Woman, Hulk, Spider-Man, X-Men and Star Wars.
==Scope==
Sir Thomas More's Utopia is one of the earliest examples of a cohesive fictional world with its own rules and functional concepts, but it comprises only one small island. Later fictional universes, like Robert E. Howard's Conan the Cimmerian stories or Lev Grossman's Fillory, are global in scope and some, like Star Wars, Honorverse, BattleTech, or the Lensman series, are galactic or even intergalactic.
A fictional universe may even concern itself with more than one interconnected universe through fictional devices such as dreams, "time travel" or "parallel worlds". Such a series of interconnected universes is often called a multiverse. Such multiverses have been featured prominently in science fiction since at least the mid-20th century.
The Star Trek episode "Mirror, Mirror" introduced the Mirror Universe, in which the crew members of the Starship Enterprise were brutal rather than compassionate. The 2009 movie Star Trek created an "alternate reality" and freed the Star Trek franchise from continuity issues. DC Comics and Marvel Comics (Superman, Batman, Wonder Woman, Teen Titans, Spider-Man, Hulk, X-Men, Fantastic Four, etc.) the comic books all of time. In the mid-1980s, DC Comics Crisis on Infinite Earths streamlined its fictional continuity by destroying most of its alternate universes.
The fictional universe of the original companies Disney, Warner Bros., DC and Marvel the animations, live-actions and comics characters (includes Mickey Mouse, Bugs Bunny, Wonder Woman and Spider-Man, among others).
==Format==
A fictional universe can be contained in a single work, as in George Orwell's Nineteen Eighty-Four or Aldous Huxley's Brave New World, or in serialized, series-based, open-ended or round robin-style fiction.
In most small-scale fictional universes, general properties and timeline events fit into a consistently organized continuity. However, in the case of universes that are rewritten or revised by different writers, editors, or producers, this continuity may be violated, by accident or by design.
The occasional publishing use of retroactive continuity (retcon) often occurs due to this kind of revision or oversight. Members of fandom often create a kind of fan-made canon (fanon) to patch up such errors; "fanon" that becomes generally accepted sometimes becomes actual canon. Other fan-made additions to a universe (fan fiction, alternate universe, pastiche, parody) are usually not considered canonical unless they get authorized.
==Collaboration==
Shared universes often come about when a fictional universe achieves great commercial success and attracts other media. For example, a successful movie may catch the attention of various book authors, who wish to write stories based on that movie. Under U.S. law, the copyright-holder retains control of all other derivative works, including those written by other authors, but they might not feel comfortable in those other mediums or may feel that other individuals will do a better job; therefore, they may open up the copyright on a shared-universe basis. The degree to which the copyright-holder or franchise retains control is often one of the points in the license agreement. 
For example, the comic book Superman was so popular that it spawned over 30 different radio, television, and movie series and a similar number of video games, as well as theme park rides, books, and songs. In the other direction, both Star Trek (including, Star Trek characters) and Star Wars (the classic stars, including, Darth Vader) are responsible for hundreds of books and games of varying levels of canonicity.
For was example, Big Two most comic book publishing companies of DC and Marvel, the four classic superheroes characters, the creators of Superman, Batman, the Incredible Hulk and Spider-Man. DC and Marvel the feature full length special edition motion picture media franchises include Superman, Batman, Wonder Woman, Spider-Man, the Incredible Hulk, the X-Men, the Fantastic Four and the Avengers.
Fictional universes are sometimes shared by multiple prose authors, with each author's works in that universe being granted approximately equal canonical status. For example, Larry Niven's fictional universe Known Space has an approximately 135-year period in which Niven allows other authors to write stories about the Man-Kzin Wars. Other fictional universes, like the Ring of Fire series, actively court canonical stimulus from fans, but gate and control the changes through a formalized process and the final say of the editor and universe creator.
Other universes are created by one or several authors but are intended to be used non-canonically by others, such as the fictional settings for games, particularly role-playing games and video games. Settings for the role-playing game Dungeons & Dragons are called campaign settings; other games have also incorporated this term on occasion. Virtual worlds are fictional worlds in which online computer games, notably MMORPGs and MUDs, take place. A fictional crossover occurs when two or more fictional characters, series or universes cross over with one another, usually in the context of a character created by one author or owned by one company meeting a character created or owned by another. In the case where two fictional universes covering entire actual universes cross over, physical travel from one universe to another may actually occur in the course of the story. Such crossovers are usually, but not always, considered non-canonical by their creators or by those in charge of the properties involved.
For lists of fictional universes see:
*List of fictional shared universes in film and television
*List of fictional universes in animation and comics
*List of fictional universes in literature
*List of science fiction universes
Category:Fiction