Fictional universe

A fictional universe—also called an imagined universe, constructed universe, or diegetic world—is a self-consistent imaginary setting that serves as the backdrop for a narrative or artistic work. This idea appears most often in fantasy and science fiction, across media like novels, comics, films, TV shows, and video games. In science fiction, the setting might be a distant alien planet or galaxy with little connection to our own reality, as seen in the Star Wars universe. In fantasy, it could be a heavily fictionalized or wholly invented version of Earth’s ancient past or far future, such as the world of The Lord of the Rings.

Fictional continuity

In a 1970 article for CAPA-alpha, comics historian Don Markstein proposed a set of criteria to define fictional universes in terms of continuity. According to his framework: if characters A and B have appeared together in a story, they share the same universe; if B and C have also met, then A and C are transitively in that universe as well. Real people cannot serve as connectors—otherwise, one could argue Superman and the Fantastic Four occupy the same universe because Superman met John F. Kennedy, Kennedy met Neil Armstrong, and Armstrong met the Fantastic Four.

Similarly, characters that do not originate with the publisher cannot link others; otherwise, both Superman and the Fantastic Four could be connected through Hercules, whom each has met. However, specific fictionalized versions of real people—for instance, the DC Comics version of Jerry Lewis, who differed from the real Jerry Lewis by having a magical housekeeper—can be used as links. The same applies to specific versions of public-domain characters, like Marvel’s Hercules or DC’s Robin Hood.

Collaboration

A meeting only counts if the characters actually appeared together in a story; simply sharing a cover does not put them in the same universe. Sometimes multiple prose authors share a fictional universe, with each writer’s contributions granted roughly equal canonical status. For example, Larry Niven’s Known Space includes a period of about 135 years during which Niven permits other authors to write stories about the Man-Kzin Wars. Other universes, such as the Ring of Fire series, actively encourage fan contributions but control changes through a formal process, with the final say held by the editor and the universe’s creator.