Jean IV de Brosse, duc d'Étampes et Chevreuse, comte de Penthièvre (1505 in Lamballe – 31 January 1565) was a French governor, military commander and courtier. The son of René de Brosse and member of a prominent Breton family that had been disgraced during the War of the Public Weal Étampes found himself pushed forward into prominence when king François I arranged a marriage between the count and his mistress Anne de Pisseleu d'Heilly. To secure his consent to this political arrangement François created for the couple the Duchy of Étampes and restored effective control of the County of Penthièvre to his family, it having been confiscated after their disgrace. In 1543 his position in Normandy, already expansive was supplemented still further with his appointment as governor of the province.