Sayyid Ruhollah Musavi Khomeini (Persian: روح الله موسوی خمینی (help·info), pronounced ) (24 September 1902 – 3 June 1989) was an Iranian religious leader and politician, and leader of the 1979 Iranian Revolution which saw the overthrow of Mohammad Reza Pahlavi, the late Shah of Iran. Following the revolution and a national referendum, Khomeini became the country's Supreme Leader—a position created in the constitution as the highest ranking political and religious authority of the nation, until his death.

Khomeini was a marja or marja al-taqlid, ("source of emulation"), (also known as a Grand Ayatollah) in Twelver Shi'a Islam, but is most famous for his political role. In his writings and preachings he expanded the Shi'a Usuli theory of velayat-e faqih, the "guardianship of the jurisconsult (clerical authority)" to include theocratic political rule by Islamic jurists.

Beloved by millions of Iranians of his time, and hated by some Khomeini was a "charismatic leader of immense popularity," and both his return from exile and his funeral were occasions of great emotional outpouring for millions. Abroad he was known for his antagonism towards imperialism and colonialism as well as his support of the hostage takers during the Iranian hostage crisis and his fatwa calling for the death of British citizen Salman Rushdie. The "virtual face of Islam in Western popular culture," Khomeini was named Man of the Year in 1979 by TIME magazine, which noted that "To Iran's Shi'ite Muslim laity, he is the Imam, an ascetic spiritual leader whose teachings are unquestioned. To hundreds of millions of others, he is a fanatic whose judgments are harsh, reasoning bizarre and conclusions surreal.". Iranian American scholar Vali Nasr believes that Khomeini was a man who "escalated anti-Americanism and inculcated fear and distrust towards Islam" during his reign.