Gian Gastone de' Medici (born Giovanni Battista Gastone; 24 May 1671 – 9 July 1737) was the seventh and last Medicean Grand Duke of Tuscany. He was the second son of Grand Duke Cosimo III and Marguerite Louise d'Orléans. His sister, Electress Palatine Anna Maria Luisa, arranged his marriage to the wealthy and widowed Anna Maria Franziska of Saxe-Lauenburg in 1697. The couple despised each other and had no children. As Grand Prince Ferdinando, Gian Gastone's elder brother, predeceased Cosimo III, Gian Gastone succeeded his father in 1723.