Duce ( DOO-chay, Italian: [ˈduːtʃe]) is an Italian title, derived from the Latin word dux 'leader', and a cognate of duke. National Fascist Party leader Benito Mussolini was identified by Fascists as Il Duce ('The Leader') of the movement since the birth of the Fasci Italiani di Combattimento in 1919. In 1925 it became a reference to the dictatorial position of Sua Eccellenza Benito Mussolini, Capo del Governo, Duce del Fascismo e Fondatore dell'Impero ('His Excellency Benito Mussolini, Head of Government, Leader of Fascism and Founder of the Empire'). Mussolini held this title together with that of President of the Council of Ministers: this was the constitutional position which entitled him to rule Italy on behalf of the King of Italy. Founder of the Empire was added for the exclusive use by Mussolini in recognition of his founding of an official legal entity of the Italian Empire on behalf of the King in 1936 following Italy's victory in the Second Italo-Ethiopian War. The position was held by Mussolini until 1943, when he was removed from office by the King and the position of "Duce" was dismantled, while Marshal Pietro Badoglio, 1st Duke of Addis Abeba was appointed Presidente del Consiglio.

This position was the model which other fascist leaders adopted, such as the position of Führer by Adolf Hitler and Caudillo by Francisco Franco. In September 1943, Mussolini styled himself as the "Duce of the Italian Social Republic" (Italian: Duce della Repubblica Sociale Italiana), and held the position until the collapse of the Italian Social Republic and his execution in April 1945.