In the "Super Mario Bros." series of video games, the primary antagonist, Bowser, is the king of the Koopas, a tribe of warrior turtles. The name "King Koopa" was used primarily in the "Super Mario Bros. Super Show" and the "Super Mario Bros." film to refer to Bowser.

The "King Koopa" name may also come from a loose translation of Bowser's original Japanese name, "Daima? Kuppa." "Daima?" is a term sometimes used in Japanese fiction for a demon king. King Koopa or Bowser is usually an enemy of Mario and Luigi and frequently takes Princess Peach hostage, but in some games, he has been an ally to the Mario brothers in the face of greater dangers.