The Joker is a fictional character, a comic book supervillain published by DC Comics and appearing as the archenemy of Batman. Created by Jerry Robinson, Bill Finger and Bob Kane, the character first appeared in Batman #1 (Spring 1940).

Throughout his comic book appearances, the Joker is portrayed as a master criminal whose characterization has varied from that of a violent psychopath to a goofy trickster-thief. He is the archenemy of Batman, having been directly responsible for numerous tragedies in Batman's life, including the paralysis of Barbara Gordon and the death of Jason Todd, the second Robin.

Throughout the character's long history, there have been several different origin tales; they most commonly depict 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 clown.

The Joker has been portrayed by Cesar Romero in the Batman TV series, Jack Nicholson in Tim Burton's Batman, and Heath Ledger in Christopher Nolan's The Dark Knight, for which Ledger posthumously won the Academy Award for Best Supporting Actor. Larry Storch, Mark Hamill, Kevin Michael Richardson and Jeff Bennett have provided the voice for the character in animated form.

Wizard's list of the 100 Greatest Villains of All Time ranked the Joker as #1. IGN's list of the Top 100 Comic Book Villains of All Time List ranked the Joker as #2. He was also named the 8th Greatest comic book character in history by Empire.