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)