Edward William Spencer Cavendish, 10th Duke of Devonshire, KG, MBE, TD (6 May 1895 – 26 November 1950), known as the Marquess of Hartington from 1908 to 1938, was a British politician. He was the head of the Devonshire branch of the House of Cavendish. He had careers with the army and in politics and was a senior freemason. His sudden death, apparently of a heart attack at the age of fifty-five, occurred in the presence of the suspected serial killer John Bodkin Adams.