Frederick William (German:Friedrich Wilhelm) (16 February 1620 – 29 April 1688) was Elector of Brandenburg and Duke of Prussia – and thus ruler of Brandenburg-Prussia – from 1640 until his death. A member of the House of Hohenzollern, he is popularly known as "The Great Elector" (German:Der Große Kurfürst) because of his military and political prowess.