Mademoiselle X is a 1945 French drama film directed by Pierre Billon and starring Madeleine Sologne, André Luguet and Ketti Gallian.

It was partly shot at the Saint-Maurice Studios in Paris. The film's sets were designed by the art directors Auguste Capelier and Georges Wakhévitch. The producer André Paulvé had recently been removed by the authorities from The Children of Paradise on account of his partial Jewish heritage and shifted to this less prestigious production, likely due to the intervention of his rival Alfred Greven of Continental Films. The film went into production In May 1944 shortly before the Liberation.