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)

Aubrey Mather

Greengrocer (uncredited)

Austin Trevor

Monocle Man (uncredited)

Charles Hawtrey

Studious Youngster (uncredited)

Martita Hunt

The Professor's Daughter (uncredited)

Torin Thatcher

Mr. Verloc's Visitor (uncredited)

Peter Bull

Mr. Verloc's Visitor (uncredited)