Sylvia Sidney

Mrs. Verloc

Oskar Homolka

Karl Verloc - Her Husband

Desmond Tester

Stevie - Her Young Brother

John Loder

Ted

Joyce Barbour

Renee

Matthew Boulton

Superintendent Talbot

S. J. Warmington

Hollingshead

William Dewhurst

The Professor

Clare Greet

Mrs. Jones (uncredited)