István Bethlen (October 8, 1874 - October 5, 1947?), was a Hungarian aristocrat and statesman and served as Prime Minister from 1921 to 1931.

The scion of a noble Transylvanian family, Bethlen was elected to the Hungarian parliament as a Liberal in 1901. Later, he served as a representative of the new Hungarian government at the Paris Peace Conference in 1919. In that year, the weak centrist Hungarian government collapsed, and was soon replaced by a communist Hungarian Soviet Republic, under the leadership of Béla Kun. Bethlen quickly returned to Hungary to assume leadership of the anti-communist "white" government based in Szeged, along with former Austro-Hungarian admiral Miklós Horthy. After the "white" forces seized control of Hungary with the help of the Romanian army, Horthy was appointed Regent. Bethlen again took a seat in the Hungarian parliament, allying with the conservative factions there.

After the attempted return of Emperor Karl I to the throne of Hungary in 1921, Horthy asked Bethlen to form a strong government to eliminate the possiblility of other such threats to the new country. Bethlen founded the Party of National Unity. Through a system of ballot manipulation, handing out government jobs, and changing the electoral law to enfranchise supporters, he was able to form a political machine that was unstoppable in Hungarian politics. Bethlen was also able to unite the two most powerful factors in Hungarian society, the wealthy, primarily Jewish industrialists in Budapest and the old Magyar gentry in rural Hungary, into a lasting coalition; this effectively checked the rise of Facism in the country for at least a decade. Bethlen was also able to reach an accord with the labor unions, earning their support for the government and eliminating a source of domestic dissent.

During his decade in office, Bethlen lead Hungary into the League of Nations and arragined a close alliance with Fascist Italy, in order to further the nation's revisionist hopes. However, he was defeated in his attempts to change the Treaty of Trianon, which stripped Hungary of most of its territory after the First World War. The Great Depression shifted Hungarian politics to the extreme right, and Horthy replaced Bethlen with Gyula Károlyi, followed quickly by Gyula Gombos, a noted Fascist and antisemite.

Increasingly shunted into political obscurity, Bethlen stood out as one of the few voices in Hungary actively opposed to an alliance with Nazi Germany. As it became apparent that Germany was going to lose the Second World War, Bethlen attempted, unsuccessfully, to negotiate a separate peace with the Allied powers. When Budapest fell to the advancing Soviet troops in April 1945, Bethlen was captured and taken to Moscow, where he was murdered with other Hungarian patriots on or around October 5, 1946.