Heinrich XI was born at Greiz, Reuss, youngest child of Count Heinrich II Reuss-Obergreiz (1696–1722), (son of Heinrich VI, Count Reuss-Greiz and Baroness Henriette Amalie von Friesen) and his wife, Countess Sophie Charlotte von Bothmer (1697–1748), (daughter of Count Hans Kaspar von Bothmer and Gisela Erdmuth von Hoym).
