The Marvel Universe is a fictional shared universe where the stories in most American comic book titles and other media published by Marvel Comics take place. Super-teams such as the Avengers, the X-Men, the Fantastic Four, the Guardians of the Galaxy, and many Marvel superheroes live in this universe, including characters such as Spider-Man, Captain America, Iron Man, Thor, the Hulk, Ant-Man, the Wasp, Wolverine, Black Panther, Doctor Strange, Daredevil, and Captain Marvel, Blade, Black Widow, Hawkeye, among numerous others. It also contains well-known supervillains such as Doctor Doom, Magneto, Ultron, Thanos, Loki, The Green Goblin, Kang the Conqueror, Red Skull, The Kingpin, Doctor Octopus, Carnage, Apocalypse, Dormammu, Mysterio, Electro, and the Vulture. It also contains antiheroes such as Venom, Namor, Deadpool, Silver Sable, Ghost Rider, The Punisher, and Black Cat.

A shared universe or shared world is a fictional universe from a set of creative works where one or more writers independently contribute works that can stand alone but fits 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 artists are working together on the same work and from crossovers where the works and characters are independent except for a single meeting.