Landgravine Marie Louise of Hesse-Kassel was a daughter of Charles I, Landgrave of Hesse-Kassel, and Maria Amalia of Courland. She was granddaughter of Duke of Courland Jackob Kettler. 

By her marriage to John William Friso, Prince of Orange, she became Princess consort of Orange, a title last held by Mary II of England. Like her husband, she is an ancestor of all currently reigning monarchs in Europe.

Marie Louise is notable for having served as Regent for two periods in Dutch history: during the reigns of her young son, William IV, Prince of Orange, and of her young grandson, William V, Prince of Orange. She was often fondly referred to as Marijke Meu (Aunt Mary) by her Dutch subjects.