A shared universe or shared world is a fictional universe from a set of creative works where one or more writers (or other artists) independently contribute works that can stand alone but fit into the joint development of the storyline, characters, or world of the overall project. It is common in genres like science fiction. It differs from collaborative writing in which multiple creators are working together on the same work and from crossovers where the works and characters are independent except for a single meeting.
The term shared universe is also used within comics to reflect the overall milieu created by the comic book publisher in which characters, events, and premises from one product line appear in other product lines in a media franchise. A specific kind of shared universe that is published across a variety of media (such as novels and films), each of them contributing to the growth, history, and status of the setting is called an "imaginary entertainment environment". (Jefferson, NC: McFarland. 2001) p. 29.
The term has also been used in a wider, non-literary sense to convey interdisciplinary or social commonality, often in the context of a "shared universe of discourse".*
Definitions Fiction in some media, such as most television programs and many comic book titles, is understood by viewers or readers to require the contribution of multiple authors and does not by itself create a shared universe and is considered a collaborative art form. Incidental appearances, such as that of d'Artagnan in Cyrano de Bergerac, are 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, often being one-offs.
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.
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".
Markstein's criteria Comics historian Don Markstein first defined the term in a 1970 article in CAPA-alpha. He laid out the following criteria:, by Don Markstein (as "Om Markstein Sklom Stu"), in CAPA-alpha #71, September 1970; archived at Don Markstein's Toonopedia 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 each other if they appeared together on-panel in a story.
Originating in print publications Originating in novels
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 prevented 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 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.
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.
Originating in comics/based upon comics
Within comics, the term shared universe has been used to reflect the overall milieu created by the comic book publisher in which characters, events, and premises from one product line appear in other product lines in a media franchise.
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. Marvel sets its stories in an increasing number of alternate realities, each with an assigned number in a greater "multiverse". DC Comics 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.
Although DC and Marvel's 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.
Universes in films and television
Universes in films (or television) mostly consist of a franchise featuring an umbrella of multiple franchises (film or television) set within the same continuity, each franchise within telling its own stand-alone story focusing on a different character (or group of characters), as well as featuring its own cast, directors, and writers, while also being a part of a coherent, non-contradictory continuity shared with the other works. Fictional universes with major presence in films are referred to as cinematic universes, while fictional universes with major presence in television are referred to as television universes. Universes with major presence in both films and television are also generally called cinematic universes. Some film and television universes are accompanied by video games, and print works such as novels or comics, telling additional canonical stories set within the same continuity.
Universes in films Following the films Son of Frankenstein (1939) and Dracula's Daughter (1935), Universal began experimenting with transfictional storytelling with their horror films series throughout the early to mid 1940s. This form was conceptualized by Richard Saint-Gelais who described it as when "two (or more) texts exhibit a transfictional relationship where they share elements, such as characters, imaginary locations, and fictional worlds."
William Proctor in Horror Franchise Cinema (2021) wrote that Universal began transfictional storytelling by applying it to the film series, but these experiments were "not always conducted as carefully or as thoroughly as audiences, especially fans, would expect in contemporary terms". This is seen in Universal's Frankenstein films, the Dracula films which are sequentially fragmented as Son of Dracula (1943) does not reference narratives or characters from either Dracula (1931) or Dracula's Daughter. Following the release of The Wolf Man (1941) and The Ghost of Frankenstein (1942), Universal released Frankenstein Meets the Wolf Man (1942) which operated as a sequel to both films. Proctor suggested that the Frankenstein Meets the Wolf Man (1942), the first crossover in film history, and the ensemble films House of Frankenstein (1944) and House of Dracula (1945) established the first "cinematic universe".
Some universes in film have originated as film adaptations of novels, such as the James Bond film series based on the spy novels by Ian Fleming. The films adapt some elements from the novels; however, they are not direct adaptations, nor were they adapted in the same order as the books were released. The first film in the series is Dr. No (1962), followed by 19 sequels until Die Another Day (2002). Due to the 20 films spanning 40 years, James Bond was portrayed by five actors, and other recurring characters have also been portrayed by multiple actors. Die Another Day was succeeded by a rebooted series consisting of five movies from Casino Royale (2006) through No Time to Die (2021), with Daniel Craig as another version of James Bond. After all of Fleming's Bond novels were adapted, the series shifted towards original scripts. Aspects of the fictional universe are retained between films.