The Sleeping Cardinal, also known as Sherlock Holmes' Fatal Hour in the United States, is a 1931 British mystery film directed by Leslie S. Hiscott and starring Arthur Wontner and Ian Fleming. The film is an adaptation of the Sherlock Holmes stories by Arthur Conan Doyle. Although it is not based on any one particular story, the film draws inspiration from "The Empty House" and "The Final Problem". The film is the first in the 1931–1937 film series starring Wontner as Sherlock Holmes. It is unrelated to the Basil Rathbone series of Sherlock Holmes films that began in the late 1930s.

The film was produced at Twickenham Studios in London with sets designed by art director James A. Carter.