Basil Rathbone

Sherlock Holmes

Nigel Bruce

Doctor Watson

Marjorie Riordan

Sheila Woodbury

Rosalind Ivan

Agatha Dunham

Morton Lowry

Steward

Leslie Vincent

Nikolas Watson

Martin Kosleck

Mirko

Rex Evans

Gregor

John Abbott

Jodri

Gerald Hamer

Kingston

William 'Wee Willie' Davis

Gubek

Frederick Worlock

Prime Minister

Tom Dillon

Matthias Cherney (uncredited)

James Carlisle

Aide (uncredited)

Olaf Hytten

Stimson (uncredited)

Roy William Neill