Sim, Peter Pettigrew era um Grifinório e um Comensal da Morte.

Peter Pettigrew era um grifinório que "ficou mal" - as memórias de Snape confirmam conclusivamente que ele era um grifinório, já que Snape estava assistindo à cerimônia de seleção e o viu se juntar à Grifinória.

“The roll call continued. Harry watched Lupin, Pettigrew and his father join Lily and Sirius at the Gryffindor table.”
_{^{- Harry Potter and the Deathly Hallows, Chapter 33 (The Prince’s Tale)}}

“Wormtail walked out of the circle to the place where Cedric’s body lay, and returned with Harry’s wand, which he thrust roughly into Harry’s hand without looking at him. Then Wormtail resumed his place in the circle of watching Death Eaters.”
_{^{- Harry Potter and the Goblet of Fire, Chapter 34 (Priori Incantatem)}}