Michael Rennie

Character: Lord John Roxton

Jill St. John

Character: Jennifer Holmes

David Hedison

Character: Ed Malone

Claude Rains

Character: Prof. George Edward Challenger

Fernando Lamas

Character: Manuel Gomez

Richard Haydn

Character: Prof. Summerlee

Ray Stricklyn

Character: David Holmes

Jay Novello

Character: Costa

Vitina Marcus

Character: Native Girl

Ian Wolfe

Character: Burton White

Colin Campbell

Character: Prof. Waldron (uncredited)

John Graham

Character: Stuart Holmes (uncredited)

Larry Chance

Character: Indian Chief (uncredited)

Bert Stevens

Character: Reporter at Airport (uncredited)

Al Bain

Character: Man at Airport (uncredited)

Bess Flowers

Character: Guest at Zoological Institute Forum (uncredited)

Kenner G. Kemp

Character: Guest at Zoological Institute Forum (uncredited)

Cosmo Sardo

Character: Guest at Zoological Institute Forum (uncredited)

Murray Pollack

Character: Guest at Zoological Institute Forum (uncredited)