Bowser is the main antagonist of the Super Mario series, and has appeared in almost every Mario title to date. In most titles, Bowser kidnaps Peach, whom is held captive until Bowser's inevitable defeat by either of the MarioBros..
In Super Mario Bros., the title that Bowser debuted in, the Koopa King was stated to be a wizard who, alongside his army known as the Koopa Troop, invaded the Mushroom Kingdom and transformed the inhabitants into inanimate objects while kidnapping Princess Peach, the only person who was able to undo the curse. In later games, he has seldom been shown with the powers stated to have in his debut, and his reasoning for kidnapping Peach has become vague, with some games stating he does it to agitate Mario, and others showing that he is infatuated with the Mushroom Kingdom's princess.
While he holds the title as the Super Mario series' main antagonist, he has also played the role of anti-hero in various Mario role-playing games. In these games, Bowser is also depicted as more comical than diabolical, unless he serves as the main antagonist of the title.