 Christopher LeeProf. Sir Alexander Saxton | Prof. Sir Alexander Saxton |
 Peter CushingDr. Wells | Dr. Wells |
 Telly SavalasCaptain Kazan | Captain Kazan |
 Alberto de MendozaFather Pujardov | Father Pujardov |
 Silvia TortosaCountess Irina Petrovska | Countess Irina Petrovska |
 Julio PeñaInspector Mirov | Inspector Mirov |
 Ángel del PozoYevtushenko | Yevtushenko |
 Helga LinéNatasha | Natasha |
 Alice ReinheartMiss Jones | Miss Jones |
 José JaspeConductor Koniev | Conductor Koniev |
| GGeorge RigaudCount Maryan Petrovski | Count Maryan Petrovski |
 Víctor IsraelLuggage Worker | Luggage Worker |
| FFaith CliftAmerican Passenger, Miss Bennett (uncredited) | American Passenger, Miss Bennett (uncredited) |
| JJuan OlaguibelCreature | Creature |
 José MarcoVorkin | Vorkin |
 José CanalejasRussian Guard | Russian Guard |
 Vicente RocaStation Master | Station Master |
| HHiroshi KitatawaGrashinski - the Locksmith (uncredited) | Grashinski - the Locksmith (uncredited) |
| BBarta BarriFirst Telegraphist | First Telegraphist |
| PPeter BeckmanSecond Telegraphist (uncredited) | Second Telegraphist (uncredited) |
| AAllen RussellCapt. O'Hagan (uncredited) | Capt. O'Hagan (uncredited) |
| FFernando Villena(uncredited) | (uncredited) |
 Robert RiettiFather Pujardov (voice) | Father Pujardov (voice) |
| OOlive GreggCountess Irina Petrovski / Natasha / Miss Jones (voice) | Countess Irina Petrovski / Natasha / Miss Jones (voice) |
 Roger DelgadoInspector Mirov (voice) | Inspector Mirov (voice) |
