William Hopper
Colonel Robert Calder
Acting
Joan Taylor
Marisa Leonardo
Acting
Frank Puglia
Dr. Leonardo
Acting
John Zaremba
Dr. Judson
Acting
Thomas Browne Henry
Maj. Gen. A.D. McIntosh
Acting
Tito Vuolo
Commissario Unte
Acting
Jan Arvan
Signore Contino - Government Official
Acting
Arthur Space
Dr. Sharman
Acting
Bart Braverman
Pepe
Acting
Don Orlando
Fisherman Mondello (uncredited)
Acting
George Khoury
Fisherman Verrico (uncredited)
Acting
Darlene Fields
Reporter Reynolds (uncredited)
Acting
George Pelling
Reporter Maples (uncredited)
Acting
James Dime
Felix Roi, a French reporter (uncredited)
Acting
Sid Cassel
Farmer (uncredited)
Acting
Ray Harryhausen
Man Feeding Elephant (uncredited)
Visual Effects
Noel Drayton
1st Reuters News Correspondent (uncredited)
Acting
Rollin Moriyama
Dr. Koruku - Japanese Scientist
Acting