Welching on me like all the others, eh? I'll teach you for backing out of a deal! HAVE AT YOU!
~ The Devil after the player refuses to give him the contracts.

The Joker King is, real name Doug Tan, is a troubled Asian American living in Gotham City and the brother of Dana Tan who tried to emulate the Joker. After years of what his parents viewed as an unhealthy obsession, Doug lost all of his Joker paraphernalia. Doug continued to be a fan of the Joker and joined the Jokerz. Doug was disgusted with the Jokerz' childish nature and the petty crimes they performed. Doug had plans to unite all the Jokerz across America and bring honor to their namesake. Doug was sent to prison for his crimes, however he was able to spread his vision.

Doug was named the Joker King and created a united force behind him. All the Jokerz coming to Gotham City was the first part of his plan. The Joker King used hypnotic drugs in a mass gathering of Jokerz to carry out mass destruction to everyone in the city. Members of the Jokerz gang were strapped with explosives and "willingly" taking out buildings along with themselves.

Joker King approached his family at the Gotham City Hospital, however they were rescued by Bruce Wayne and Terry McGinnis. Joker King was about to kill Batman until he was rescued by Dick Grayson.

During the final showdown between him and Batman, Joker King's foot was accidentally caught by some rope and he fell off the ledge. The swing from the rope caused Doug's body to slam against the concrete wall of an unfinished building which killed him. Joker King was then smiling in the end.