John Carradine
Dr. Sigmund Walters
Evelyn Ankers
Beth Colman
Milburn Stone
Fred Mason
Lloyd Corrigan
John Whipple
Fay Helm
Nurse Strand
Martha Vickers
Dorothy Colman
Acquanetta
Paula Dupree, the Ape Woman
Vince Barnett
Curly
Paul Fix
Gruen
Fred Aldrich
Roustabout (uncredited)
Clyde Beatty
Fred Mason (in long shots) (archive footage / uncredited)
Turhan Bey
End Narrator (voice)(uncredited)
Eddie Borden
Dock Spectator (uncredited)
Ray Corrigan
Cheela the Gorilla (uncredited)
Russell Custer
Curley (uncredited)
Fern Emmett
Beth's Murdered Neighbor (uncredited)
Virginia Engels
Trapeze Artist (uncredited)
Alexander Gill
Waiter (uncredited)
Gus Glassmire
Coroner (uncredited)
Joel Goodkind
Small Boy (uncredited)
William Gould
Sheriff (uncredited)
Al Haskell
Al (uncredited)
Harry Holman
Dock Ticket Office Clerk
Tom London
Ship's Captain (archive footage)
Charles McAvoy
Cop (uncredited)
Frank Mitchell
Handler (uncredited)
Charles Morton
Dock Worker (uncredited)
Edward Peil Sr.
Jake - Handler (uncredited)
Stanley Price
Man on Dock (uncredited)
Joey Ray
Attendant (uncredited)
Cap Somers
Roustabout (uncredited)
Ray Walker
Ringmaster (uncredited)
Anthony Warde
Tony - Handler (uncredited)
Grant Withers
Veterinarian (uncredited)