Real Identity: Unknown
Appearances: Galaxy Jest
Powers/Skills: Planning and Engineering
Voiced By: Mark Hamill
The Joker is the Clown Prince of Crime, one of Batman's greatest enemies, and Gotham City's most notorious criminal. He often employs deadly weapons housed in innocent looking objects. The Joker plotted to make all of Gotham City break out into laughter with his Gutbuster bomb, an oversized clown doll that housed 50,000 tons of his Super Laughing Gas. He hid the Gutbuster in a clock tower, linked the timer to the tower's clock gears, and set it to blow at midnight. The Joker rode around his wagon taunting Batman that the clock was ticking. After crashing into some railing and nearly driving into the harbor, Joker squeezed out the window and declared finding parking was always a pain. Just as the Batmobile arrived, Joker was caught in a tractor beam and taken aboard Mongul's space crusier in space. Batman hailed the Justice League for assistance. While Superman and Wonder Woman went after the Joker, Batman and the Flash continued to search the city with less than an hour left. Joker discovered he was chosen to entertain an audience of warriors or he would die.
The Joker dispensed with his material but he didn't get any laughs. Mongul jumped down into the arena. Joker revealed he had a zinger and held out his hand to shake. Mongul was zapped with a joy buzzer. The warriors gasped then broke out into laughter. Mongul, however, was enraged and decided to throw Joker out of an airlock into space. Luckily, Superman was waiting. He blasted Mongul with heat vision and "secured" the Joker. Mongul returned and attacked Superman. Joker cheered on Superman but was disgusted with himself. Eventually, he slipped away and found the docking bay. He boarded Wonder Woman's spacecraft. As he tried to figure out the controls, Joker's face was lassoed by Wonder Woman. The Flash and Superman came to Batman's aid when the Gutbuster detonated. Superman inhaled the Super Laughing Gas and exhaled it into Mongul's cruiser. Wonder Woman threw the Joker into one of the Gotham City Police Department's wagons as he offered himself to entertain at the Justice League's next holiday party.