The Man in the Iron Mask is a 1939 American historical adventure film very loosely adapted from the last section of the 1847–1850 novel The Vicomte de Bragelonne by Alexandre Dumas, père, which is itself based on the French legend of the Man in the Iron Mask.

The Man in the Iron Mask was an unidentified prisoner of state during the reign of King Louis XIV of France (1643–1715). Warranted for arrest on 28 July 1669 under the pseudonym of "Eustache Dauger", he was incarcerated on 24 August and held for 34 years in the custody of the same jailer, Bénigne Dauvergne de Saint-Mars, in four successive French prisons, including the Bastille. When he died there on 19 November 1703, his inhumation certificate bore the pseudonym of "Marchioly", leading several 19th century historians to conclude the prisoner was Italian diplomat Ercole Antonio Mattioli.