Liam Neeson has a minor role in a great movie called The Mission back in 1985, which starred Jeremy Irons and Robert DeNiro.
And the fantasy movie Krull before that (along with Hagrid himself, Robbie Coltrane)
Daniel Craig was a snotty teenage drug dealer in Drop The Dead Donkey many moons ago...
David Boreanaz got punched out by Ed O'Neill as Kelly's boyfriend in Married With Children
Tony Head was a Nazi in Secret Army in about 1979...