The Great Sebastian is a magician who performs at The Drunken Clam in "Meg's Wedding", specializing in up-close magic. He tries to perform a card trick with Peter, who is unable to see the cards. Giving up, he accidentally sets Peter's hair aflame and then puts it out with his vest. But when he departs, he leaves the vest behind, so Peter decides to start wearing it.
The Great Sebastian is voiced by Josh Robert Thompson.