Captain America is a superhero created by Joe Simon and Jack Kirby who appears in American comic books published by Marvel Comics. The character first appeared in Captain America Comics #1, published on December 20, 1940, by Timely Comics, a corporate predecessor to Marvel. Captain America's civilian identity is Steve Rogers, a frail man enhanced to the peak of human physical perfection by an experimental "super-soldier serum" after joining the United States Army to aid the country's efforts in World War II. Equipped with an American flag-inspired costume and a virtually indestructible shield, Captain America and his sidekick Bucky Barnes clashed frequently with the villainous Red Skull and other members of the Axis powers. In the final days of the war, an accident left Captain America frozen in a state of suspended animation until he was revived in modern times. He resumes his exploits as a costumed hero and becomes leader of the superhero team the Avengers, but frequently struggles as a "man out of time" to adjust to the new era.

A superhero or superheroine is a stock character who typically possesses superpowers or abilities beyond those of ordinary people, is frequently costumed concealing their identity, and fits the role of the hero; typically using their powers to help the world become a better place, or dedicating themselves to protecting the public and fighting crime. Superhero fiction is the genre of fiction that is centered on such characters, especially, since the 1930s, in American comic books, as well as in Japanese media.