Joker

The Joker is a supervillain who was a major threat to both the heroes and villains. He is accompanied by Harley Quinn most of the time.

Happy Hour
Joker's first major role began in Happy Hour. He is at odds with Green Goblin due to the latter's affinity for Harley. Joker spikes every hero's drink with nanomachines capable of mental manipulations. After rewiring Lance's circuitry to his control, Joker brainwashed the heroes into thinking their parents were shot in front of them, just like Batman. Joker was eventually stopped by Goblin, Batman, and Spider-Man.

Zero Hour
In a post-credits scene of the Happy Hour finale, Joker was revealed to have been teleported to Apokolips, and is subsequently interrogated by Darkseid. This would later become a full episode. Joker is then annihilated by Darkseid's omega beams after he reveals to Darkseid that he's a fictional character (as Darkseid thought he was real).

Darkseid then revived Joker as his own lackey. Joker renamed himself Joe Pagliacci, a reference to the opera, but the name was lost in translation and he was instead referred to as Joe Palachi instead. Palachi became a spokesperson of Apokoliptian technology. In Zero Hour episode 6, Palachi meets up with the villains, claiming to give them Apokoliptian weapons. When Dr. Doom questions the ludicrosity of Palachi being revived just to sell weapons, Palachi corrects him by saying he's not selling them weapons, he ''using it on them. ''He turns the villains into eldritch monsters. Near the end of Zero Hour episode 7, Palachi accidentally shoots Darkseid's reboot device (a bullet intended for Deadpool but Goblin saved him) and activates it. Palachi is struck by the device, reverting him back to the Joker.

Personality
Joker largely retains his comic book characteristics. He is a selfish, arrogant, calculating, and evil murderer willing to do anything to achieve his goals. However, RandomGuy made Joker more sinister in this incarnation, hardly making any wisecracks like he's known to.