Evil Sheen is Sheen's evil clone and Evil Libby's boyfriend. He lived on the Evil Earth. He also joined the angry mob of evil kids who wanted to kill Jimmy when he was accidentally being polite. He and the other evil clones were then sucked into the Dark Matter Dimension with the Evil Earth after Evil Jimmy broke the dark matter power chip that made everyone on that planet just as evil as Evil Jimmy.
He looks and sounds exactly like Good Sheen but unlike Good Sheen, he loves Robo-Fiend and hates Ultra Lord. However, he is still wearing an Ultra-Lord shirt, even though he should be wearing a Robo Fiend one. This could be because it would've taken too long to model one.
In the planned season four, Evil Sheen and the other evil clones would've returned from the Dark Matter Dimension and attacked Jimmy and his class, who were on a field trip to the moon provided by Jimmy himself.