Curtis Base

History
Curtis Base attempted but failed to kill the original Joker. Base and the original Joker end up battling for exclusive right to be called the Joker. The fight ends between the two in a draw as Wayne as Batman basically ends the struggle and takes the original into custody and Base rarely resurfaces as the second Joker after his second run in with the original.

Currently it is presumed that Base is dead or changed his mind to succeed the Joker.

Powers and Abilities
Base has no known superhuman powers but seems to be immune to the original Joker's venom.