Shared universe

Definitions

Fiction in media such as most television programs and many comic book titles requires multiple authors and is considered collaborative, not automatically a shared universe. Incidental appearances, like d'Artagnan in Cyrano de Bergerac, are literary cameos. More substantial interactions between characters from different sources are marketed as crossovers; while crossovers occur in shared universes, not all are intended to merge back-stories and may be one-offs for marketing, parody, or 'what-if' scenarios.

Maintaining consistency becomes difficult as a shared universe grows, and the version deemed official by the controlling author or company is called canon. Not all shared universes have a controlling entity determining canonicity, and fans may develop a fanon consensus. Tools like retconning, short for 'retroactive continuity,' correct contradictions from multiple contributors over time. Readers may object when a story is integrated into a shared universe, feeling it requires fans of one hero to buy other heroes' titles.

Comics historian Don Markstein defined the term in a 1970 article, laying out criteria: if characters A and B have met, and B and C have met, then A and C are in the same universe; characters cannot be connected by real people or by characters that do not originate with the publisher.

Originating in print publications

Expansion of existing material into a shared universe is not limited to licensed settings. Larry Niven opened his Known Space setting to other writers, initially due to his lack of military experience, but later clarified it was to be used only under restricted circumstances with permission, as with the Man-Kzin Wars series. Eric Flint expanded his 1632 series by editing and publishing collaborations with fan fiction writers. Posthumous expansion, such as August Derleth's development of the Cthulhu Mythos from H. P. Lovecraft's writings, is considered by some to be completely dissimilar to Lovecraft's own works.

Less controversial examples include sequels to L. Frank Baum's Oz stories and further development of Isaac Asimov's Foundation universe by Greg Bear, Gregory Benford, and David Brin. Many such works take the form of short-story anthologies with occasional standalone novels, like Robert Lynn Asprin's Thieves' World, C. J. Cherryh's Merovingen Nights, and Janet Morris' Heroes in Hell.

Universes in films and television

Universes in films or television mostly consist of a franchise featuring multiple franchises set within the same continuity, each telling its own stand-alone story focusing on a different character or group, with its own cast, directors, and writers, while sharing a coherent continuity. Fictional universes with major presence in films are called cinematic universes; those in television are television universes, though universes in both are generally called cinematic universes.

Some are accompanied by video games, novels, or comics telling additional canonical stories. Universal began experimenting with transfictional storytelling with their horror film series in the early to mid 1940s, as conceptualized by Richard Saint-Gelais. William Proctor wrote that these experiments were not always conducted as carefully as audiences would expect, noting fragmentation in Universal's Frankenstein and Dracula films. Frankenstein Meets the Wolf Man (1942) operated as a sequel to both The Wolf Man (1941) and The Ghost of Frankenstein (1942), and Proctor suggested that this film, along with House of Frankenstein (1944) and House of Dracula (1945), established the first cinematic universe.

Other media

A shared universe can bring together separate works under one fictional umbrella. The musical Seussical, from 2000, treated various Dr. Seuss stories as part of one world. Hasbro considers its G.I. Joe and Transformers toys to exist within its own Hasbro Universe, which also includes comic book universes from IDW Publishing and Skybound Entertainment. In music, journalists and media outlets have described Taylor Swift’s songs, albums, videos, and tours as a musical or cinematic universe.