The Devil is the main antagonist of Sinfest.

The Devil is a manipulative trickster who possesses the ability to transform people into devils, an ability that either Jesus or Buddha can reverse. He often makes deals with Slick which would often cause him to go to Hell. He is also seen bickering with God, and believing that people were created to make Himself look better, and it's been shown that he envies the relationship between God and Jesus. He also has drones that spy for him. It is revealed in a recent strip that he is the father of his self-proclaimed biggest fan Lil' Evil. He was married to an unamed woman in white. He was disappointed that Lil' Evil didn't act as malevolent as he was. He also has a hobby of hunting cherubs in an Elmer Fudd-like manner. He also seems to possess a weakness by not being able, or unwilling to go into a dimension called the Reality Zone.