A shared universe is a fictional universe in which multiple works are set. One or more authors may contribute works to a shared universe. The works within the universe may share characters, settings, and other story elements, with or without continuity. Shared universes can be found in literature, comic books, films, television, anime and manga and are most commonly seen in fantasy and science fiction genres.
- 1 Definitions
- 2 Characteristics
- 3 Expansion of existing material
- 4 Original settings
- 5 List of shared universes
- 6 See also
- 7 References
There is no formal definition of when the appearance of fictional characters in separate works constitutes a shared universe. Fiction in some media, such as most television programs and many comic book titles, is understood to require the contribution of multiple authors and does not by itself create a shared universe. Incidental appearances, such as that of d'Artagnan in Cyrano de Bergerac, may instead be considered literary cameo appearances. More substantial interaction between characters from different sources is often marketed as a crossover. While crossovers occur in a shared universe, not all crossovers are intended to merge their settings' back-stories and are instead used for marketing, parody, or to explore "what-if" scenarios.
The modern definition of copyright, especially under United States copyright law, considers the expansion of a previous work's setting or characters to be a derivative work. This often necessitates licensing agreements for new material being considered for publication (unless the author is the same). For this reason, fan fiction and other amateur works written in established settings without permission are sometimes distinguished from shared universe writings or described as employing a "stolen universe". However, fair use claims have been raised and not all authors believe that fan fiction should be distinguished from other literature in this manner.
In a process similar to brand licensing, the intellectual property owners of established fictional settings at times allow others to author new material and create an expanded universe. Such franchises, generally based on television programs or film, allow for the creation and distribution of novels, video games, original sound recordings and other media based on the original product. However, not all shared universe settings are simply the expansion or combination of pre-existing material by new authors. At times, an author or group of authors engineer a setting specifically for development by multiple authors, often through collaboration.
Continuity methods and issues
It can become difficult for writers contributing to a shared universe to maintain consistency and avoid contradicting details in earlier works, especially when a shared universe grows to be very large. The version deemed "official" by the author or company controlling the setting is known as canon. Not all shared universes have a controlling entity capable of or interested in determining canonicity, and not all fans agree with these determinations when they occur. A fanon may instead find some degree of consensus within the setting's fandom.
Some writers, in an effort to ensure that a canon can be established and to keep details of the setting believable, employ tools to correct contradictions and errors that result from multiple contributors working over a long period of time. One such tool is retconning, short for "retroactive continuity", which resolves errors in continuity that came about through previously-written conflicting material. While most retcons serve to preserve continuity, a more severe form of retcon involves a wholesale rewrite of the groundwork for the entire setting. These reboots, most closely associated with DC Comics, are not always effective at resolving underlying problems and may be met with a negative reaction from fans.
Contributors to expanded universes, also known as tie-in writers, have sometimes been stereotyped as "hacks" because such writing is perceived as less creative or of consistently poor quality. These stereotypes have been disputed by authors who consider contributing to a larger work "intellectually demanding." The inclusion of professional and award-winning authors in this category have also done much to change public perception of writing in a shared universe.
Readers may also object when a story or series is integrated into a shared universe, feeling it "requir[es] one hero's fans to buy other heroes' titles", or leads to mischaracterizations and inappropriate comparisons.
Expansion of existing material
In 1941, writer Gardner Fox at All-American Comics (later part of DC Comics) created the Justice Society of America in All-Star Comics #3, credited with being the first superhero team-up and laying the groundwork for the DC Universe, the first comic book shared universe. By 1961, Marvel Comics writer and editor Stan Lee, working with artists Jack Kirby and Steve Ditko, merged the bulk of the publisher's comics characters into the Marvel Universe. Both settings have suffered from the creative difficulties of maintaining a complex shared universe handled by large numbers of writers and editors. DC has substantially altered its in-universe chronology several times, in series such as Crisis on Infinite Earths in 1985, Zero Hour in 1994, and Infinite Crisis in 2005. As of 2007, Marvel has rebooted its continuity only once, in Spider-Man: One More Day. They instead set stories in an increasing number of alternate realities, each with an assigned number in a greater "multiverse". DC and Marvel have also periodically co-published series in which their respective characters meet and interact. These intercompany crossovers have typically been written as self-limiting events that avoid implying that the DC Universe and Marvel Universe co-exist. Exceptions include the twenty-four comics released under the metafictional imprint Amalgam Comics in 1996, depicting a shared universe populated by hybridizations of the two companies' characters. Marvel has since referred to this as part of its setting's greater multiverse by labeling it Earth-692.
The Star Wars franchise takes a unique view regarding the canon properties of its expanded universe, introducing a four-tier system based on compatibility with the original six films. Star Trek canon is less well-defined, generally excluding not only licensed works such as books and video games and acknowledging that "even events in some of the movies have been called into question". Both franchises have blurred the lines between canon and non-canon content by adopting unofficial material into later official productions. 
The spin-off media extending of the universe originating in Doctor Who is particularly complex due to the permissive stance on licensing and canon taken by the BBC. This expanded universe has relatively little consistency given its division into audio plays produced by Big Finish and the BBC, the New Adventures universe novel, or a universe based on comics published in Doctor Who Magazine and other publications. Reviewer Robert F.W. Smith attempted to summarize the conflicting continuities:
"As far as I understand it, the situation is this: the New Adventures universe is inside the bottle universe seen in Interference, which was built by BBC universe Time Lords, and in it, the NA Time Lords are all gone – they’ve gone to another bottle and left the NA universe to the Gods/Kings of Space. Most of the New Adventures happened in the BBC universe anyway, except in that universe, the 7th Doctor was the reincarnation of the Other and Rassilon escaped to roam the universe – in the BBC universe, he may or may not have been, and Rassilon probably didn’t. In the BBC universe, Faction Paradox, the Doctor and the Enemy between them have vaped the Time Lords, with the result that there are no longer any Time Lords in the BBC universe, except for five, the fundamental laws of the universe (the magic-and-science thing) have changed, and the Doctor is no longer a Time Lord at all originally but a crystal man named Soul from the end of time. Also in the BBC universe, an infinity of different universes have been released, which helpfully explains how all the shock companion-killings in the novels ever since Eternity Weeps either did or didn’t happen in our universe, according to whatever criteria you like, but Gallifrey didn’t survive in any of them. Despite this, Gallifrey will still be rebuilt in the BBC universe in some form, but it will presumably be much less powerful because it will now be a planet without the original’s special relationship with time, and it won’t have always been there. Where the Big Finish audios fit in is anybody’s guess; the new series can just about be assumed to follow on from the end of The Gallifrey Chronicles, even though the Doc says he’s a Time Lord – not a crystal man from the end of time – in the second episode. There."
Even Smith's summary does not address spin-offs such as the Bernice Summerfield novels and the Faction Paradox series that are legally distinct from the origins of their characters in officially licensed novels. Many fans consider only the television series canon and all other media apocrypha. The television series has never explicitly acknowledged any of the spin-offs, partly because the BBC's status as a public service broadcaster prohibits them from producing a program that can only be fully understood by those who have purchased licensed products. Since 2005, modern episodes of the program have made both purist and fully inclusive positions relatively difficult, as they refer to concepts, characters and species introduced in comic books, audio dramas and novelizations, while also directly adapting Expanded Universe content depicting older Doctors into new episodes starring the television actors of the day.
The expansion of existing material into a shared universe is not restricted to settings licensed from movies and television. For example, Larry Niven opened his Known Space setting to other writers initially because he considered his lack of military experience to prevent him from adequately describing the wars between mankind and the Kzinti. The degree to which he has made the setting available for other writers became a topic of controversy, when Elf Sternberg created an erotic short story set in Known Space following an author's note from Niven indicating that "[i]f you want more Known Space stories, you'll have to write them yourself". Niven has since clarified that his setting is still to be used only "under restricted circumstances and with permission", which Niven granted to the several authors of the Man-Kzin Wars series. By contrast, author Eric Flint has edited and published collaborations with fan fiction writers directly, expanding his 1632 series.
A setting may also be expanded in a similar manner after the death of its creator, although this posthumous expansion does not meet some strict definitions of a shared universe. One such example is August Derleth's development of the Cthulhu Mythos from the writings of H. P. Lovecraft, an approach whose result is considered by some to be "completely dissimilar" to Lovecraft's own works. Less controversial posthumous expansions include Ruth Plumly Thompson's and later authors' sequels to L. Frank Baum's Oz stories and the further development of Isaac Asimov's Foundation universe by Greg Bear, Gregory Benford, and David Brin.
Although DC and Marvel's successful shared universe approaches to comics have set them apart from competitors in the industry, other companies have attempted similar models. Valiant Comics and Crossgen both produced titles primarily set from their inception in a single, publisher-wide shared universe, known respectively as Unity and the Sigilverse.
Many other published works of this nature take the form of a series of short-story anthologies with occasional standalone novels. Examples include Robert Lynn Asprin's Thieves' World, C. J. Cherryh's Merovingen Nights and Janet Morris' Heroes in Hell.
Role-playing games are inherently designed to include some aspects of the shared universe concept, as individual games are derived from the core material. Campaign settings, such as Dungeons & Dragons's Faerûn, Dragonlance and Eberron, provide a more detailed world in which novels and other related media are additionally set. Living campaigns, including the RPGA's Living Greyhawk or the AEG-sanctioned Heroes of Rokugan, provide an opportunity for individual games hosted worldwide to take part in a single continuity.
The influence of the Internet on collaborative and interactive fiction has also resulted in a large number of amateur shared universe settings. Amateur authors have created shared universes by contributing to mailing lists, story archives and Usenet. One of the earliest of these settings, SFStory, saw its spin-off setting Superguy cited as illustrative of the potential of the Internet. Another example is the furry-themed Tales from the Blind Pig created at the Transformation Story Archive, which differs from many amateur settings both by having an organized effort to maintain consistent canon and by having seen some limited publication. Other early examples include the Dargon Project and Devilbunnies.
At least one publisher has introduced a division specifically for encouraging and handling shared universe fiction.
- J. R. R. Tolkien's legendarium comprising The Hobbit and The Lord of the Rings
- H. P. Lovecraft's Cthulhu Mythos
- Isaac Asimov
- Simon R. Green's Deathstalker universe
- Stephen King's novels and short stories
- Uplift Universe by David Brin
- David Mitchell's universe explained in his novels Black Swan Green and The Bone Clocks
- Rick Riordan's Percy Jackson & the Olympians (its spin-off The Heroes of Olympus) and The Kane Chronicles
- Agatha Christie's universe
- C. J. Cherryh
- The Liaden universe by Sharon Lee and Steve Miller
- The Mortal Instruments and The Bane Chronicles by Cassandra Clare
- Noon Universe by Arkady and Boris Strugatsky
- Sime – Gen Universe by Jacqueline Lichtenberg
- Larry Niven's Known Space
- L. Frank Baum's Oz franchise
- Eric Flint's Assiti Shards series
- S. M. Stirling's Nantucket and Emberverse series
- Janet Morris's Heroes in Hell
- Sergei Lukyanenko's Draft Universe
- Thomas Hardy's Wessex
- J. K. Rowling's Harry Potter
- R. Scott Bakker's The Prince of Nothing and The Aspect-Emperor
- Brandon Sanderson's The Cosmere includes Elantris, The Stormlight Archive series and other works.
All Bret Easton Ellis novels share places timelines and characters including Camden, a fictional college
- DC Universe
- Marvel Universe
- Amalgam Universe
- Image Universe
- Valiant Universe
- CrossGen Universe
- 2000 AD and Judge Dredd
- Donald Duck universe
A film universe is a derivative of the shared universe that applies to films. Notable examples of the film universe include:
- Universal Monsters Cinematic Universe
- The Showa era of Toho's daikaiju films, including Godzilla, Mothra, and the television series Zone Fighter.
- The original Superman films starring Christopher Reeve, and its spin-off Supergirl
- Alien, Predator, Alien vs. Predator and Prometheus
- Kevin Smith's View Askewniverse
- The X-Men film series
- The Librarian franchise
- The Marvel Cinematic Universe comprising the Avengers films, short films and television series and other related media.
- The DC Comics' shared universe films comprising the films, Man of Steel, Batman v Superman: Dawn of Justice, and future Justice League films.
- Most of the DC Universe Animated Original Movies take place in different universes, with the exception of:
- Jim Henson's The Muppets and Sesame Street
- The Beverly Hillbillies, Petticoat Junction and Green Acres
- The Whoniverse, comprising Doctor Who and related media
- The Star Trek, universe comprising the original series and its four spin-off television series and 12 movies.
- Adam-12, Emergency! and Sierra
- Cannon and Barnaby Jones
- Battlestar Galactica (1978-1980; rebooted in 2004)
- Diff'rent Strokes, The Facts of Life and Hello, Larry
- Magnum, P.I., Simon & Simon. Whiz Kids, Murder, She Wrote and The Law & Harry McGraw
- Cheers, The Tortellis, Wings and Frasier
- L.A. Law and Civil Wars
- Matlock, Mission: Impossible, Mannix, Jake and the Fatman, Diagnosis: Murder and Promised Land
- The Law & Order franchise
- Mad About You, Friends and Joey
- Power Rangers, Masked Rider and Ninja Turtles: The Next Mutation
- The X-Files, Millennium and The Lone Gunmen
- NYPD Blue, Public Morals and Brooklyn South
- Walker, Texas Ranger and Sons of Thunder
- ER, Third Watch and Medical Investigation
- The JAG/NCIS universe comprising the series JAG and its spin-off franchise NCIS, alongside three tie-ins (First Monday, Hawaii Five-0, and Scorpion)
- The Practice, Ally McBeal, Gideon's Crossing, Boston Public and Boston Legal
- The Buffyverse, comprising Buffy the Vampire Slayer and spin-off Angel
- Dawson's Creek and spin-off Young Americans
- The CSI franchise comprising CSI: Crime Scene Investigation, its three spin-offs (Miami, NY and Cyber) and two tie-ins (Without a Trace and Cold Case)
- Crossing Jordan and Las Vegas
- The Firefly franchise
- Disney Channel sitcoms produced by It's a Laugh Productions such as That's So Raven and spin-off Cory in the House; The Suite Life of Zack & Cody, its sequel The Suite Life on Deck and spin-off Jessie; Hannah Montana, Wizards of Waverly Place, I'm in the Band, Good Luck Charlie, Shake It Up, Austin & Ally and Liv and Maddie share the same universe.
- One Tree Hill and Life Unexpected
- Nickelodeon sitcoms such as Drake & Josh, Zoey 101, iCarly, Victorious and Sam & Cat share the same universe.
- Prison Break and Breakout Kings
- Eureka, Warehouse 13 and Alphas
- Flashpoint and The Listener
- Pretty Little Liars and spin-offs Pretty Dirty Secrets and Ravenswood
- All seasons of American Horror Story shared the same timeline.
- Arrow and spin-off The Flash
An animated universe is a derivative of the shared universe that applies to animated works, including animated television series and films, which share the same characters and continuity with each other. It may also derive from the characters and continuity of previous literary serial works, including comics, and thus may be termed the same as the literary work it was derived from. Notable examples of the animated universe include:
- Looney Tunes and Merrie Melodies
- Several Hanna-Barbera cartoons have also shared the same universe. These are The Flintstones, The Jetsons, Scooby-Doo, Yogi Bear, Huckleberry Hound, Quick Draw McGraw, Top Cat, Wacky Races, etc. as well as the Archie Comics property Josie and the Pussycats and the DC Comics property Super Friends
- Masters of the Universe, which included He-Man and She-Ra in the 1980s
- Series produced by Sunbow Entertainment, including and G.I. Joe: A Real American Hero, The Transformers, Jem and the Holograms, and Inhumanoids
- Most of Nickelodeon's animated properties
- DC animated universe (1992–2006)
- Marvel's animation universes that included crossovers between multiple series
- Disney Channel's animated properties such as
- Most of Cartoon Network's animated properties
- Space Ghost Coast to Coast, Aqua Teen Hunger Force, The Brak Show and Harvey Birdman, Attorney at Law
- Dexter's Laboratory and The Powerpuff Girls
- Cow and Chicken and I Am Weasel
- The Grim & Evil franchise, comprising the series The Grim Adventures of Billy & Mandy and Evil Con Carne
- Ben 10 and The Secret Saturdays
- Family Guy, American Dad! and The Cleveland Show (1999–present)
Anime and manga
Japan has also created many animated universes:
- Akira Toriyama's various serious including Dr. Slump, Dragon Ball and his other one-shot manga series (1979-2007)
- Gundam "metaseries" (1979–present)
- Mazinger has crossed over with other robot fighter anime such as Devilman, Getter Robo and Grendizer
- Scramble Wars universe included AD Police, Bubblegum Crisis, Gall Force and Riding Bean
- Super Dimension series
- Brave series of the 90s particularly had GaoGaiGar spawning Betterman in the same universe
- Gokinjo Monogatari and its spinoff Paradise Kiss
- Outlaw Star and Angel Links (1998-1999)
- Higurashi When They Cry and Umineko: When They Cry have a character in common
- Fate/stay and Tsukihime have a character in common, and most other works by Type-Moon and stories by Kinoko Nasu have more or less distant links between them.
- Reki Kawahara's universe consists of Sword Art Online and Accel World
- The CLAMP group's series including Cardcaptor Sakura, Tsubasa Chronicle and xxxHolic among others
- Dijiko and Puchiko of Di Gi Charat are also characters in Cromartie High School (episode 25)
- A Certain Magical Index and its spin-offs A Certain Scientific Railgun and A Certain Scientific Accelerator
- Marvel Mangaverse
- The Marvel Anime universe comprising four anime series and two films.
- Detective Conan and Magic Kaito
- Nintendo's properties:
- Grand Theft Auto and Manhunt by Rockstar Games
- Half-Life and Portal by Valve Corporation
- Eve Online by CCP Games
- Dead or Alive and the Ninja Gaiden reboot by Tecmo
- Dynasty Warriors, Samurai Warriors and Warriors Orochi by Koei
- King's Field and Demon's Souls by From Software
- Hero Universe by Hero Games
- Ubisoft's properties:
- Jump Super Stars and Jump Ultimate Stars
- Crash Bandicoot and Spyro the Dragon
- Jak & Daxter, Ratchet & Clank and Sly Cooper
- Sega Super All-Stars
- The Mega Man franchise by Capcom
- Pac-Man, Dig Dug, Klonoa, Baraduke and Mr. Driller by Namco
- Fictional universe
- Expanded universe
- Fictional crossover
- Setting (narrative)
- Tommy Westphall Universe
- Wold Newton Universe
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