The Joker is a character.
Joker (character) . Introduced as a psychopath with a warped , sadistic sense of humor , the character became a goofy prankster in the late 1950s in response to regulation by the Comics Code Authority , before returning to his darker roots during the early 1970s . One of the most iconic characters in popular culture , the Joker has been listed among the greatest comic book villains and fictional characters ever created .