Marguerite Brunet, known by her stage name of Mademoiselle Montansier (19 December 1730, Bayonne - 13 July 1820, Paris), was a French actress and theatre director.
At 14 she fled from the Ursuline convent in Bordeaux, she was there engaged by an acting troupe and — in love with a handsome young actor — embarked for America. She then became the mistress of Burson, Intendant of Martinique, establishing her own dress shop in Saint-Domingue. On her return to Paris, she installed herself in the house of an aunt by marriage, Mme Montansier, a dress-seller from whom she took her stage name. She opened a gaming house on the rue Saint-Honoré, frequented by the gilded youth of Paris and allowing her to enter high society.
Having obtained through her liaison with the marquis de Saint-Contest the leadership of a small theatre on rue Satory in Versailles, she turned her attention to queen Marie-Antoinette and through her in 1775 gained the exclusive rights to balls and shows at the Palace of Versailles, followed in 1779 by rights over the theatres in Fontainebleau, Saint-Cloud, Marly, Compiègne, Rouen, Caen, Orléans, Nantes and Le Havre. Backed by such supporters, she built her first theatre at Versailles - at first called "Théâtre de la rue des Réservoirs", but soon renamed "Théâtre Montansier" - which she opened on 18 November 1777 in the presence of Louis XVI and his queen.