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)

Alfred Hitchcock
Man Walking Past the Cinema as the Light Is Renewed