A fictional universe is a made up world that is used as the setting for one or (more commonly) many works of fiction. It is often used in books but can be used in any form used to tell a story, for example role-playing games, television or movies. It can be said that every work of fiction makes a world of its own. A fictional universe is used when things in a story become a part either of other stories, or of games or other things.

Fictional universes are most often used in science fiction and fantasy stories but they can be used in any type of fiction. A fictional universe usually has certain things in them that make them different from the real world. These things could affect anything from cities the author created to entire galaxies. In most fictional universes, the laws of physics are different to let things exist which commonly do not, for example, magic or space travel to other planets. Fictional universes may also take place in any time period during the past, present, or future.

Definition
The term was first defined by comics historian Don Markstein, in a 1970 article in CAPA-alpha.

Markstein's criteria
 Characters that meet are in the same universe.
 Characters cannot be connected by real people
 Specific fictionalized versions of real people can be used as connections
Characters "meet" if they appear together in a story.

Examples of fictional universes
There are many examples of fictional universes. They are often used to provide a common theme to many different types of things.

The Star Wars expanded universe
The Star Wars expanded universe is a fictional universe that was started from the first Star Wars movie Star Wars Episode IV: A New Hope in 1977.

The Buffyverse 
Based on Buffy the Vampire Slayer the television series.

Many types of fiction have their own "universe". Many started in one category and now exist in many of them. For example, Harry Potter started out as a series of books then moved to movies and then video games.

Movies and television
Back to the Future - Time travel
Star Trek - Space travel and futuristic technology
Alien - Aliens and space travel

Video games
Grand Theft Auto - Fictional cities that are analogous to each other such as Liberty City to New York City or Los Santos to Los Angeles
Final Fantasy - Fantasy creatures and magic
Resident Evil - Zombies and other creatures
The Warcraft series and World of Warcraft - Fantasy creatures and magic

Books
Harry Potter - Magic
Middle-earth - artificial myth, fantasy creatures
The Marvel Universe used in Marvel Comics - super-human powers such as flying, aliens, magic, technology

Role-playing games
Forgotten Realms - Fantasy creatures and magic
Dragonlance - Dragons and magic

Locations
Batman comics - Gotham City
Superman comics - Metropolis
Wonder Woman comics - Themyscira
The Simpsons show - Springfield
Futurama show - New New York City
Mickey Mouse universe - Mouston
Donald Duck universe - Duckby
The Flintstones show - Bedrock
SpongeBob SquarePants show - Bikini Bottom
South Park show - South Park
Arthur show - Elmwood City, Crown City
Adventure Time show - The Candy Kingdom

List of Shared Universes
Marvel Cinematic Universe (22 films)
DC Extended Universe (9 films)
Dark Universe (3 films)
The Conjuring Universe (8 films)
Eastrail 177 Trilogy (3 films)
Disney Live Action Reimaginings (14 films)

Abandoned shared universes:

The reboots of  A Nightmare on Elm Street,  Friday the 13th and  The Texas Chainsaw Massacre shared a universe, the New Line Cinema's House of Horror which was cancelled following disappointing figures and reviews

Related pages
Fictional character

References

 
Children's literature
Fantasy movies