The Joker is a super-villain and arch-nemesis of Batman. Since the Golden Age of Comic Books, he has remained as one of the most popular and threatening figures in the DC Universe. His personality is often conflicting and contradictory, switching from a mass-murdering psychopath to a harmless prankster on a whim, making him extremely unpredictable. Though he usually does not star in his own series, Joker is usually seen alongside the caped crusader in many of his books.