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 unnamed 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. Despite this, the Devil secretly surveillances his son, even though he is at the same time disappointed that he is far from becoming evil like he desires for him. He also seems to possess a weakness by not being able, or unwilling to go into a dimension called the Reality Zone.
By the time that the Sisterhood arc dominated the webcomic, the Devil was subsequently rewritten as being the vile ruler over the Patriarchy who had made it his goal of oppressing women in anyway he sees fit. Prior to this, it was heavily implied that the reason as to why he would select certain women into becoming succubi is to appeal to a man's preferences. For instance, Absinthe, a green Devil Girl who was appointed to replace Fuchsia after she had fallen in love with Criminy and left, primarily because she would appeal to some men's preferences for a moe-esque woman. The Devil oversees the sex industry, and is the overall backer behind the entire industry. He had also formed a rivalry with Xanthe, the leader of the Sisterhood, and this rivalry would be delved upon continually during the webcomic's history. He also seems to have become aware of Vainglorious, an incubus with an unknown past, whose goal is to overthrow the Devil and take over.