The Destroyer of Worlds was one of the Arcade Games that Mordecai and Rigby discovered in the episode "Just Set Up The Chairs" of the cartoon series Regular Show.
He appears to be nothing more than a pixelated floating devil head.
Powers and Abilities
He can shoot fire from his eyes and floats in midair. He seems to be invulnerable to anything that isn't digital (an example of this is when Rigby tosses a rock at him - it bounces off of him and he gets mad).
The Destroyer of Worlds
Mordecai was unwilling to touch it because of both the 'out of order' sign on the front and the note apparently written by Skips, warning them not to connect the red wire with the blue wire. Rigby, being the idiot that he is, connected them anyway, releasing a giant demon head that began to float around and set everything on fire. Destroyer of Worlds was later defeated by Rigby, who was just "mashing the buttons" on a system created by Skips in which a giant protagonist was created by joining all the other Arcade Games together.