William IV, Landgrave of Hesse-Kassel (d. 1573)
William IV of Hesse-Kassel (24 June 1532 – 25 August 1592), also called William the Wise, was the first Landgrave of the Landgraviate of Hesse-Kassel (or Hesse-Cassel). He was the founder of the oldest line, which survives to this day.