Evil Coop is the ultimate villain from Megas XLR, appearing in the two-part final episode, "Rearview Mirror Mirror". He is the self-proclaimed ruler of the Alternate Earth that Coop and Gorrath fall into during a heated fight.
After he defeated Gorrath and his Glorft army, Coop (before he became evil) kept fighting, conquering planet after planet. He eventually lost his human side, got into shape and ditched Megas. Up until Coop's intervention, Evil Coop was constantly trying to destroy the last piece of human resistance, which was led by Alternate Jamie. During the final battle with the real Coop and the Glorft, Coop and Evil Kiva were trapped in the Lurp Dimension