Ethan is a monster that lived in Stewie Griffin's closet until kicked out in "Mom's the Word". When Stewie becomes concerned about the reality of death following the passing of his grandmother Thelma Griffin, Brian is surprised at Stewie's fear and points out that he had always been fearless before, even ignoring the monster in the closet. Stewie points out that he is evicting the monster for breaking their agreement about subletting. As Ethan steps out to protest, Ethan's monster roommate tells him to drop the pretense as they had been caught.

Ethan is voiced by John Viener.