Joker

The Joker is a supervillain and the archenemy of Batman. First introduced in Batman #1 (Spring 1940), he was originally a criminal mastermind with a devious sense of humor. Initially intended to serve as a one-time appearances, Joker's instant popularity ensured that the character would continue to appear, becoming a frequent enemy of the Dark Knight and Robin, the Boy Wonder. By the late 1940s, Joker had been reimagined as a harmless prankster. Falling into obscurity by the 1960s, he was re-introduced in the 1970s as a more legitimate threat and one of the most infamous criminals within Gotham City. In recent years, the character has taken on the persona of an evil-incarnate, simply taking joy in tormenting Batman or trying to push him into villainy.