The Robot Devil is the supreme ruler of Robot Hell. He spends the most of his time rehearsing musical numbers with his robotic minions.
In "War of the Villains", The Robot Devil was recieved a visit from The Lord of the Dead, Hades, outraged at the disgrace he gives the undead. The Robot Devil decided to make a deal with Hades that if he defeat a randomly-selected robot from his Wheel of Robots, he could rule Robot Hell. Hades accepted, and much to The Robot Devil's surprise, it landed on his own name (Which he only added to show good faith for the other robots). When Hades stated if he was too chicken to fight him, the mechinized monster scoffed at him and kicked him into a pit of molten lava.
It is unknown what will happen later to The Robot Devil, though creator JamesS92692 DOES plan on reusing him at a later date.