Clayface is number 73 - IGN

The villainous Clayface is one of Batman's oldest foes. The first iteration of the character, Basil Karlo, first appeared in Detective Comics #40 (1940).

Perhaps the Caped Crusader has been unable to rid Gotham of this threat because he doesn't know where to start. There have been more versions of Clayface than drummers for Spinal Tap - there have been six, actually.

The original, re-emergent, and ultimate incarnation, is a failed actor named Basil Karlo. He was the star of a classic horror film that was scheduled for a remake. While remakes of horror movies are rarely good news, Karlo took it especially hard. He donned the mask of Clayface, the villain he played in the movie, and began killing the new cast and crew. Before long, he was apprehended by the dynamic duo and left to rot in Arkham Asylum.

Other criminals adopted his persona, but with a strange twist. Sondra Fuller's clay-like body was able to change shapes, and Preston Payne's corrosive body could melt others with a touch. This duo eventually broke Karlo out of prison. Through a blood transfusion, Karlo gained their powers and suddenly became a very real threat to Gotham. Batman has faced no shortage of Clayfaces over the years, but Karlo could be the most dangerous.