 Walter PidgeonDr. Edward Morbius | Dr. Edward Morbius |
 Anne FrancisAltaira Morbius | Altaira Morbius |
 Leslie NielsenCommander John J. Adams | Commander John J. Adams |
 Warren StevensLt. 'Doc' Ostrow | Lt. 'Doc' Ostrow |
 Jack KellyLt. Jerry Farman | Lt. Jerry Farman |
 Earl HollimanCookie | Cookie |
 Richard AndersonChief Engineer Quinn | Chief Engineer Quinn |
 George D. WallaceBosun | Bosun |
 Robert DixCrewman Grey | Crewman Grey |
 Jimmy ThompsonCrewman Youngerford | Crewman Youngerford |
 James DruryCrewman Strong | Crewman Strong |
| HHarry Harvey Jr.Crewman Randall | Crewman Randall |
| RRoger McGeeCrewman Lindstrom | Crewman Lindstrom |
 Peter MillerCrewman Moran | Crewman Moran |
 Morgan JonesCrewman Nichols | Crewman Nichols |
| RRichard GrantCrewman Silvers | Crewman Silvers |
 James BestCrewman (uncredited) | Crewman (uncredited) |
 William BoyettCrewman (uncredited) | Crewman (uncredited) |
 Les TremayneNarrator (voice) (uncredited) | Narrator (voice) (uncredited) |
 Frankie DarroRobby the Robot (interior) (uncredited) | Robby the Robot (interior) (uncredited) |
 Marvin MillerRobby the Robot (voice) (uncredited) | Robby the Robot (voice) (uncredited) |
 Robby the RobotRobby the Robot | Robby the Robot |
