Powell performed stuntwork in several films for Hammer Studios, serving as a regular stunt double for Christopher Lee. His credits during this time included portraying Thompson in Daleks' Invasion Earth 2150 A.D. (1966) and the Mummy in The Mummy's Shroud (1967). He also appeared in several James Bond films.
Powell portrayed the Aliens for stuntwork in Alien (1979) and Aliens (1986). He also did stunts in Indiana Jones and the Last Crusade (1989), Batman (1989), and Robin Hood: Prince of Thieves (1991). He had an uncredited part as The Goat of Mendes in The Devil Rides Out (1968).