Dr. Morbius
Altaira Morbius
Commander Adams
Lt. 'Doc' Ostrow
Lt. Farman
Chief Quinn
Cook
Bosun (as George Wallace)
Crewman Grey (as Bob Dix)
Crewman Youngerford
Crewman Strong
Crewman Randall
Crewman Lindstrom
Crewman Moran
Crewman Nichols
Crewman Silvers
Robby the Robot (as Robby The Robot)
Crewman (uncredited)
Robby the Robot (uncredited)
Robby the Robot (voice) (uncredited)
Narrator (voice) (uncredited)