Dr. Sigmund Walters
Beth Colman
Fred Mason
John Whipple
Nurse Strand
Dorothy Colman
Paula Dupree, the Ape Woman
Curly
Gruen
Roustabout (uncredited)
Fred Mason (in long shots) (archive footage / uncredited)
End Narrator (voice)(uncredited)
Dock Spectator (uncredited)
Cheela the Gorilla (uncredited)
Curley (uncredited)
Beth's Murdered Neighbor (uncredited)
Trapeze Artist (uncredited)
Waiter (uncredited)
Coroner (uncredited)
Small Boy (uncredited)
Sheriff (uncredited)
Al (uncredited)
Dock Ticket Office Clerk
Ship's Captain (archive footage)
Cop (uncredited)
Handler (uncredited)
Dock Worker (uncredited)
Jake - Handler (uncredited)
Man on Dock (uncredited)
Attendant (uncredited)
Roustabout (uncredited)
Ringmaster (uncredited)
Tony - Handler (uncredited)
Veterinarian (uncredited)