A superhero (also known as a "super hero" or "super-hero") is a fictional character "of unprecedented physical prowess dedicated to acts of derring-do in the public interest." Since the debut of Superman in 1938 by Jerry Siegel and Joe Shuster, stories of superheroes — ranging from brief episodic adventures to continuing years-long sagas — have dominated American comic books and crossed over into other media. A female superhero is sometimes called a "superheroine."

By most definitions, characters need not have actual superhuman powers to be deemed superheroes, although sometimes terms such as "costumed crimefighters" are used to refer to those without such powers who have many other common traits of superheroes.

For a list of comic book supervillain debuts, see List of comic book supervillain debuts.