Sebastien, Duke of Penthievre

Sebastien de Luxembourg, count, later duke of Penthièvre was duke of Penthievre and a peer of France.

Nephew of Jean de Brosse, duc d'Étampes, he was allowed to inherit his uncle's taken estates and was subsequently created the 1st Duke of Penthievre.

His daughter and heiress Marie de Luxembourg married Philippe-Emmanuel de Lorraine, duc de Mercoeur, the rebel in Brittany.