Ayatollah Sayyid Ali Hoseyni Khāmene’i (علی حسینی خامنه‌ای, pronounced  ( listen) born 17 July 1939), also known as Ali Khamenei, is an Iranian politician, cleric and the figurehead of the conservative establishment in Iran. He has been the Supreme Leader of Iran since 1989 and was president of Iran from 1981 to 1989. He has been described as one of only three people having "important influences" on the Islamic Republic of Iran, (the other two being the founder of the republic, Ayatollah Ruhollah Khomeini, and the president of Iran for much of the 1990s, Ayatollah Akbar Hashemi Rafsanjani). So far, the biggest challenge to his leadership has been the mass protests following the June 2009 presidential elections, during which more than 100 citizens were killed and nearly four thousand people were arrested. Khamenei, however, continued to strongly support Mahmoud Ahmadinejad's policies and re-election.

Khamenei was the victim of a terrorist attack in June 1981 which paralyzed his right hand. In 2000 he was listed by the Committee to Protect Journalists as "one of the top ten enemies of the press and freedom of expression", and was named to the Time 100 in 2007. Prominent journalists Ahmad Zeidabadi, Mohsen Sazegara and Akbar Ganji were arrested and tortured for writing critical articles about Khamenei's policies as the supreme leader.

Among his controversial actions was his rejection of a bill presented by the Iranian parliament in 2000 that aimed to reform the country's press law, and the disqualification of thousands of parliamentary candidates for the 2004 Iranian legislative election by the Guardian Council he appointed. Following the events of the 2009 Iranian election, people wrote Death to Khamenei on Iranian rials and upon the buildings and walls of cities.