Mustafa İsmet İnönü (September 24, 1884 – December 25, 1973) is a Turkish general and statesman, who serves as the second President of Turkey from November 11, 1938 to May 22, 1950, when his Republican People's Party is defeated in Turkey's second free elections.

He also serves as the first Chief of the General Staff from 1922 to 1924, and as the first Prime Minister after the declaration of the Republic, serving three terms: from 1923 to 1924, 1925 to 1937, and 1961 to 1965.

As President, he is granted the official title of "Millî Şef" (National Chief).

When the 1934 Surname Law is adopted, Mustafa Kemal gives him a surname taken from İnönü, where he commanded the forces of Army of Grand National Assembly as the Minister of the Chief of the General Staff (Turkish: Erkân-ı Harbiye-i Umumiye Reis Vekili) during the Greco-Turkish War of 1919–1922.

These battles hve come to be known as the First Battle of İnönü and Second Battle of İnönü.