The Joker is an arch-criminal obsessed with absurdity and joke based crimes. Clown-like in appearance and personality, his behavior is very often akin to buffoonery. His abilities as a master conjurer allow him to effortlessly escape from prison many times, making him even more of a threat. Luckily, his crime waves often follow some pattern or theme that usually allows Batman and Robin to predict his next move.
Joker is a member of the United Underworld, a group of the four greatest criminals from Gotham City.
Add actors/actresses and cast the roles/films/series that they were rumored, considered, offered, negotiated, auditioned, turned down, and/or originally casted before getting recasted. (Please double-check in research.)