Hugo William Koehler (July 19, 1886 – June 17, 1941) (pronounced [ˈkøːlɐ]) was a United States Navy commander, secret agent and socialite. Following the First World War, he served as an Office of Naval Intelligence and State Department operative in Russia during its civil war, and later as naval attaché to Poland. He was rumored to be the illegitimate son of the Crown Prince of Austria and to have assisted the Romanovs in fleeing Russia following the revolution of 1917. He was awarded the Navy Cross for his service during World War I and was the step-father of United States Senator Claiborne Pell (1918–2009).