The Joker is a fictional character appearing in comic books published by DC Comics. Debuting in Batman #1 (Spring 1940), he was created by Bill Finger, Bob Kane and Jerry Robinson. An archenemy of the superhero Batman, the Joker is portrayed as a master criminal whose characterization has varied from a violent sociopath, who kills people and commits crimes for his own amusement, to a goofy and virtually harmless trickster-thief. He has also been directly responsible for numerous tragedies in Batman's life; including, but not limited to, the paralysis of Barbara Gordon and the death of Jason Todd. The Joker's real identity is unknown. Throughout the character's long history, there have been several different origin tales; the most common theme depicts him as falling into a vat of chemical waste, which bleaches his skin and turns his hair green and his lips bright red, giving him the appearance of a macabre clown. The Joker has appeared in numerous Batman-related media including portrayals by Cesar Romero, Jack Nicholson, and Heath Ledger, and animated versions with voice actors Mark Hamill and Kevin Michael Richardson. Wizard Magazine's list of the 100 Greatest Villains of All Time ranked the Joker as #1. (via Wikipedia)