Marguerite Louise d'Orléans (28 July 1645 – 17 September 1721) was Grand Duchess of Tuscany, as the wife of Grand Duke Cosimo III de' Medici. Deprived of her lover, Charles V of Lorraine, Marguerite Louise despised her husband and his family, whom she often quarrelled with and falsely suspected of attempting to poison her. Marguerite Louise reconciled with the Medici on more than one occasion, however, only to promptly resume hostilities.