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 Alfred Hitchcock Director Bernard Knowles Director Pen Tennyson Director