Esmond Marcus David Romilly (10 June 1918 – 30 November 1941) was a British socialist, anti-fascist, and journalist, who was in turn a schoolboy rebel, a veteran with the International Brigades during the Spanish Civil War and, following the outbreak of the Second World War, an observer with the Royal Canadian Air Force. He is perhaps best remembered for his teenage elopement with his distant cousin Jessica Mitford, the second youngest of the Mitford sisters.