Mark didn't take long to work in the supernatural genre. His third role was in The X-Files Season 1, Episode 11, "Fire," as Bob the Caretaker/Cecil L'Ively. Judging by the photo, he was the main baddie of the installment.
Castiel: It's very complex. If the pizza man truly loves this babysitter, why does he keep slapping her rear? Perhaps she has done something wrong. Dean: Are you watching porn? Why? Castiel: It was there. Dean: You don't watch porn in a room full of dudes. And you don't talk about it. Just turn it off. Well now he's got a boner.