gian gastone de' medici (24 may 1671 – 9 july 1737) was the last medici grand duke of tuscany. he was the second son of cosimo iii de' medici, grand duke of tuscany and marguerite louise d'orléans. his sister, anna maria luisa de' medici, the electress palatine, married him to anna maria franziska of saxe-lauenburg in 1697. the two remained childless and it was common knowledge that gian gastone was homosexual. gian gastone succeeded his father as grand duke in 1723.