Benito Amilcare Andrea Mussolini (Italian pronunciation: [beˈniːto mussoˈliːni]; 29 July 1883 – 28 April 1945) was an Italian politician, journalist, and leader of the National Fascist Party, ruling the country as Prime Minister from 1922 until his ousting in 1943. He ruled constitutionally until 1925, when he dropped all pretense of democracy and set up a legal dictatorship. Known as Il Duce ("the leader"), Mussolini was the founder of fascism.

In 1912 Mussolini was the leading member of the National Directorate of the Italian Socialist Party (PSI). Prior to 1914 he was a keen supporter of the Socialist International, starting the series of meetings in Switzerland that organised the communist revolutions and insurrections that swept through Europe from 1917. Mussolini was expelled from the PSI due to his opposition to the party's stance on neutrality in World War I. Mussolini denounced the PSI, and later founded the fascist movement. Following the March on Rome in October 1922 he became the youngest Prime Minister in Italian history until the appointment of Matteo Renzi in February 2014. After destroying all political opposition through his secret police and outlawing labor strikes, Mussolini and his fascist followers consolidated their power through a series of laws that transformed the nation into a one-party dictatorship. Within five years he had established dictatorial authority by both legal and extraordinary means, aspiring to create a totalitarian state. Mussolini remained in power until he was deposed by King Victor Emmanuel III in 1943. A few months later, he became the leader of the Italian Social Republic, a German client regime in northern Italy; he held this post until his death in 1945.