Evelyn Ankers as Beth Mason

J. Carrol Naish as Dr. Carl Fletcher

Samuel S. Hinds as Coroner

Lois Collier as Joan Fletcher

Milburn Stone as Fred Mason

Douglass Dumbrille as District Attorney

Acquanetta as Paula Dupree, the Ape Woman

Nana Bryant as Miss Gray

Pierre Watkin as Dr. Meredith

Christian Rub as George

Richard Davis as Bob Whitney

Edward M. Hyans Jr. as Willie

Alec Craig as Caretaker

Tom Keene as Joe, the Fingerprint Man

Vince Barnett as Curley (archive footage / uncredited)

Clyde Beatty as Fred Mason (in long shots) (archive footage / uncredited)

Wilson Benge as Court Stenographer (uncredited)

John Carradine as Dr. Sigmund Walters (archive footage / uncredited)

Diane Carroll as Inquest Juror (uncredited)

Edward Clark as Inquest Juror (uncredited)

Heinie Conklin as Inquest Juror (uncredited)

Ray Corrigan as Cheela (archive footage / uncredited)

Fern Emmett as Beth's Neighbor (archive footage / uncredited)

Nolan Leary as Inquest Juror (uncredited)

Charles Marsh as Inquest Juror (uncredited)

Beatrice Roberts as Inquest Juror (uncredited)

Ray Walker as Ringmaster (archive footage / uncredited)