J. Carrol Naish
Dr. Carl Fletcher
Lois Collier
Joan Fletcher
Douglass Dumbrille
District Attorney
Acquanetta
Paula Dupree, the Ape Woman
Pierre Watkin
Dr. Meredith
Edward M. Hyans Jr.
Willie
Tom Keene
Joe, the Fingerprint Man
Vince Barnett
Curley (archive footage / uncredited)
Clyde Beatty
Fred Mason (in long shots) (archive footage / uncredited)
Wilson Benge
Court Stenographer (uncredited)
John Carradine
Dr. Sigmund Walters (archive footage / uncredited)
Diane Carroll
Inquest Juror (uncredited)
Edward Clark
Inquest Juror (uncredited)
Heinie Conklin
Inquest Juror (uncredited)
Ray Corrigan
Cheela (archive footage / uncredited)
Fern Emmett
Beth's Neighbor (archive footage / uncredited)
Nolan Leary
Inquest Juror (uncredited)
Charles Marsh
Inquest Juror (uncredited)
Beatrice Roberts
Inquest Juror (uncredited)
Ray Walker
Ringmaster (archive footage / uncredited)