Ned Dennehy. Actor: Good Omens. Ned Dennehy (born 8 December, 1965) is an Irish actor in British, Irish, and American films and television. His most notable film role to date is Tommy in Tyrannosaur. He has also appeared in the television series Mystic Knights of Tir na Nog. Other movies include Blitz, he played Alderton in Harry Potter and the Deathly Hallows - Part 1 and the independent British feature...