Sayyid Ruhollah Mūsavi Khomeini, known in the Western world as Ayatollah Khomeini, was an Iranian Shia Muslim religious leader, philosopher, revolutionary and politician. He was the founder of the Islamic Republic of Iran and the leader of the 1979 Iranian Revolution that saw the overthrow of the Pahlavi monarchy and Mohammad Reza Pahlavi, the Shah of Iran. Following the revolution, Khomeini became the country's Supreme Leader, a position created in the constitution of the Islamic Republic as the highest-ranking political and religious authority of the nation, which he held until his death.
On 1 February 1979 Ayatollah Ruhollah Khomeini, returned to Iran after 14 years in political exile. Khomeini had been a prominent opponent of Mohammad Reza Shah Pahlavi, who had fled the country during the events of the Iranian Revolution. Upon his return, he was greeted by crowds of millions, and within 10 days the revolution would be successful. Khomeini's return and the 10 days following are now celebrated in Iran as the Fajr decade.