Guest Stars Howard Caine as Leon Chambers Robert Duvall as Louis Mace William O'Connell as The Creature Douglas Henderson as Dr. Tillyard Henry Brandon as General Crawford Uncredited Roy Jenson as Gunman Dean Smith as Second Creature Bob Johnson voices Loudspeaker Person Bob Johnson voices Chopper Pilot Vic Perrin voices Soldier Christopher Riordan as Young Doctor Roy Olvera as Mexican Guitarist
