The Joker

The Joker (identity unknown, voiced by Mark Hamill) is a villain from the Batman comics, movies, and TV shows. He is considered to be The Dark Knight's greatest foe, as well as one of the greatest villains in general. Although we never know his real name, he was apparently a stand-up comedian who became the villain The Red Hood. During one fight with Batman, he tries to escape by jumping into a vat of chemicals. This transforms him into The Joker. He has a girlfriend named Harley Quinn.

The Joker is one of the Bugs and Daffy's Adventures gang's biggest foes. Apparently, on the set of the Batman show, the Looney Tunes (mostly Daffy, along with Yakko, Wakko, and Dot) drove the actors playing him and Harley to go insane, thus becoming their roles. They teamed up with Bugs and the gang's old enemies; Elmer Fudd, Marvin the Martian, and Yosemite Sam, to plot revenge.

Trivia

 * The Bugs and Daffy's Adventures gang will first face The Joker in Bugs and Daffy's Adventures of The Emperor's New Groove.