Doug Tan was a troubled youth who admired the Joker and wanted nothing more than to emulate him. After years of admiration, Tan's parents got rid of all of Tan's Joker paraphernalia, viewing it as an unhealthy obsession. Tan's idolization of the Joker continued, however, eventually leading Tan to join up with the Jokerz.

Tan was dissatisfied with the childish nature of the gang and the petty crimes they committed. Tan had plans to make unite the various Jokerz around the country and bring honor to their namesake. Eventually Tan was imprisoned and while incarcerated he was able to spread his vision. Soon Tan was named the Joker King and had a united force behind him. Bringing all the Jokerz to Gotham City was phase one of his plan. The Joker King used hypnotic drugs in a mass gathering of Jokerz to carryout mass destruction on Gotham's infrastructure. Members of the Jokerz gang were strapped with explosives and "willingly" taking out buildings along with themselves. Joker King confronts his family at a hospital, but they are saved by the combined efforts of Bruce and Terry. Later Joker King gets the upper hand on Batman, but he is saved by Dick Grayson. After a final showdown between Batman and the Joker King his reign of terror ends when his foot is caught by some rope and he falls off the ledge. The swing from the rope causes Tan's body to slam against the concrete wall of an unfinished building. The trauma inflicted to Tan's head kills him instantly with a smile the Joker King meets his end.