The Mysterious Mister X (German: Der geheimnisvolle Mister X) is a 1936 German comedy film directed by J.A. Hübler-Kahla and starring Ralph Arthur Roberts, Annemarie Steinsieck and Herti Kirchner.
The film's sets were designed by the art director Gustav A. Knauer and Alexander Mügge.
A British lord, fascinated by crime, spends his time collecting artefacts. He is thrilled when he receives mysterious letters warning that a thief plans to steal a valuable statue from his country house. His secretary persuades him to bring in her fiancée, a private detective, to investigate the case.