The Ninth Guest, sometimes abbreviated as The 9th Guest, is a 1934 American pre-Code murder mystery film directed by Roy William Neill and starring Donald Cook and Genevieve Tobin. The film is an adaptation of the 1930 Broadway play The Ninth Guest by Owen Davis, which in turn is based on the 1930 novel, The Invisible Host, by Bruce Manning and Gwen Bristow. The book, play and film all predate Agatha Christie's extremely successful 1939 novel And Then There Were None, which has a similar plot.