Wilhelm VI, Landgrave of Hesse-Kassel, known as William the Just, was Landgrave of Hesse-Kassel from 1637 to 1663.

William V, a member of the House of Hesse, was Landgrave of Hesse-Kassel from 1627 to 1637. Having come to rule in unfavorable circumstances and in the midst of the Thirty Years' War, he continued to suffer losses of territory and wealth.