The Testament of Dr. Mabuse (German: Das Testament des Dr. Mabuse) is a 1933 German crime film directed by Fritz Lang. The movie is a sequel to Lang's silent film Dr. Mabuse the Gambler (1922) and features many cast and crew members from Lang's previous films. The film features Rudolf Klein-Rogge as Dr. Mabuse who is in an insane asylum where he is found frantically writing his crime plans. When Mabuse's criminal plans begin to be implemented, Inspector Lohmann (played by Otto Wernicke) tries to find the solution with clues from gangster Thomas Kent (Gustav Diessl), the institutionalized Hofmeister (Karl Meixner) and Professor Baum (Oscar Beregi Sr.) who becomes obsessed with Dr. Mabuse.

The Testament of Dr. Mabuse was based on elements of author Norbert Jacques' novel Mabuse's Colony. It was Lang's second sound film for Nero-Film and was his final collaboration with his wife and screenwriter Thea von Harbou. To promote the film to a foreign market, a French-language version of the film was made by Lang with the same sets but different actors with the title Le Testament du Dr. Mabuse.

When Adolf Hitler acquired power, Joseph Goebbels became minister of the Ministry of Propaganda and banned the film in Germany, suggesting that the film would decrease the audience's confidence in its statesmen. The French-language and German-language versions of the film were released in Europe while several versions of the film were released in the United States to mixed reception with each re-release. The sequel The Thousand Eyes of Dr. Mabuse was released during 1960 and was also directed by Lang. Modern reception of the film is favorable with critics, while the film has influenced filmmakers including Claude Chabrol and Artur Brauner.