William I, Elector of Hesse was the eldest surviving son of Frederick II, Landgrave of Hesse-Kassel and Princess Mary of Great Britain, the daughter of George II. Wikipedia
Born: June 3, 1743, Kassel, Germany
Died: February 27, 1821 (age 77 years), Kassel, Germany
Great grandchildren: Prince Alexander of Prussia, Prince George of Prussia, George II, Duke of Saxe-Meiningen, and more
Grandparents: William VIII, Landgrave of Hesse-Kassel, George II of Great Britain, Caroline of Ansbach, and more