Louis III (9 June 1806, Darmstadt - 13 June 1877, Seeheim) was Grand Duke of Hesse and by Rhine from 1848 until his death. He was succeeded by his nephew, en:Louis IV of Hesse-Darmstadt. He was the son of Grand Duke Louis II of Hesse and his consort Wilhelmine of Baden. In 1833, he married Princess Mathilde of Bavaria, eldest daughter of Ludwig I of Bavaria. The marriage produced no children and the Grand Duke remarried in 1868 to Baroness Magdalen of Hochstadten.