While his allegiance is never made explicit, it is implied that he is a supporter of the Death Eaters. In a discussion with Arthur Weasley, he is revealed to have discovered the falsified genealogy for Dirk Cresswell. Harry uses Polyjuice Potion to impersonate him to enter into the Ministry and steal Slytherin's locket.
Actor: The son of a Scottish construction worker, O'Hara memorably played the 'mad' Irishman Stephen in Braveheart. He become William Wallace's (Mel Gibson) trusted friend and guardian after proclaiming of Ireland, "It's my island". He also appeared as Fitzy, one of Jack Nicholson's chief mobsters in the Oscar winning film The Departed.