Blackmail is a 1929 British crime thriller film directed by Alfred Hitchcock and starring Anny Ondra, John Longden, and Cyril Ritchard. Based on the 1928 play of the same name by Charles Bennett, the film is about a London woman who is blackmailed after killing a man who tries to rape her.

After starting production as a silent film, British International Pictures decided to adapt Blackmail into a separate sound film. It became the first successful European talkie; a silent version was released for cinemas not equipped for sound (at 6,740 feet), with the sound version (7,136 feet) released at the same time. Both versions are held in the British Film Institute collection.

Blackmail is frequently cited as the first British sound feature film. It was voted the best British film of 1929 in a UK poll the year it was released. In 2017 a poll of 150 actors, directors, writers, producers and critics for Time Out magazine ranked Blackmail as the 59th best British film ever.

On January 1st, 2025, the film's copyright expired in the United States, and is now in the public domain.