House: Gryffindor, 3rd Year
Dean and Seamus are Gryffindor boys that share a dorm room with Harry, Ron, and Neville. We don't see much of these boys in this novel, though they crop up occasionally in the various classes, including Divination. Like the other Gryffindors we see, these kids are friendly, have it in for Snape and Slytherins in general, and seem to get along well with Harry and his pals.
(Click the character infographic to download.)