Mascarose I of Armagnac

Mascarose I (c. 1214–before 25 March 1246) was suo jure Countess of Armagnac and Fézensac in 1245–1246, the daughter of Count Géraud V. She married her cousin Arnaud Odon of Lomagne, by whom she had a daughter, Mascarose II.

When her brother Bernard V died in 1245 she inherited the counties, but their cousin Géraud of Fézensaguet claimed women could not inherit and warred on the couple, backed by Raymond VII of Toulouse while Henry III of England supported Mascarose.