SATAN

Satan is an articulate, charismatic villain who seems to have an obsessive interest in claiming Michael's soul. Well, at least that's how Michael imagines him to be. 

Yes, Satan is merely a reflection of Michael's paranoia, driven by a fierce persecution complex.

What's caused this? Well, maybe it's that pet tarantula he didn’t receive as a child.

Satan can be seen regularly throughout episodes sitting in his comfortable leather recliner in hell while monitoring Michael on his large Plasma screen.

The dark prince is doing the usual things like plotting and scheming as all evil devils do and coughing up witty and compelling satirical observations over Michael's bizarre antics.