Michael Rennie
Lord John Roxton
Jill St. John
Jennifer Holmes
David Hedison
Ed Malone
Claude Rains
Prof. George Edward Challenger
Fernando Lamas
Manuel Gomez
Richard Haydn
Prof. Summerlee
Ray Stricklyn
David Holmes
Jay Novello
Costa
Vitina Marcus
Native Girl
Ian Wolfe
Burton White
Colin Campbell
Prof. Waldron (uncredited)
John Graham
Stuart Holmes (uncredited)
Larry Chance
Indian Chief (uncredited)
Bert Stevens
Reporter at Airport (uncredited)
Al Bain
Man at Airport (uncredited)
Bess Flowers
Guest at Zoological Institute Forum (uncredited)
Kenner G. Kemp
Guest at Zoological Institute Forum (uncredited)
Cosmo Sardo
Guest at Zoological Institute Forum (uncredited)
Murray Pollack
Guest at Zoological Institute Forum (uncredited)