The Saint's Double Trouble is a 1940 action-adventure film produced by RKO Pictures. The film stars George Sanders as Simon Templar, a.k.a. "The Saint", a master criminal turned crime-fighter, and features horror film legend Bela Lugosi as "The Partner". This was the fourth of eight films in RKO's film series about the character created by Leslie Charteris, and the first film to not be directly based upon one of the original Saint books, although Charteris did contribute to developing the story for the film.

In this production, Sanders plays a dual role, not only that of Templar but of his doppelgänger, Duke Bates. When Bates is spotted smuggling diamonds into the US, Templar is blamed for the crime.

Co-starring in the film is Helene Whitney as love interest Anne Bitts, and Jonathan Hale as Insp. Henry Farnack.