Moktada al- Sadr (mŏŏkh´tädä ä-sä´dər), 1973?–, Iraqi Shiite cleric. The son of Grand Ayatollah Mohammed Sadeq al-Sadr, who was assassinated in 1999 (presumably by Saddam Hussein's secret police), he emerged after the American invasion of Iraq as a savvy, militantly Islamist and anti-American leader, with significant support among poorer and younger Iraqi Shiites, particularly in the Sadr City section of Baghdad, a Shiite enclave named for his father. Accused of involvement in the assassination (2003) of Ayatollah Abdul Majid al-Khoei, a moderate who had U.S. support, Sadr led his militia, the Mahdi Army, in two abortive uprisings against the U.S. occupation in 2004.

After the 2004 uprisings, he supported involvement in the political process, despite denouncing the constitution, and was a significant force in the United Iraqi Alliance, a coalition of Shiite religious parties, but in Sept., 2007, his party withdrew from the government. In late 2007 he ordered his militia, which had at times fought with U.S. forces and had been blamed for attacks on the police, on Sunnis, and on other Shiites, to observe a cease-fire. His forces were significantly weakened in May, 2008, when U.S. and Iraqi government forces asserted control over Sadr City.

Sadr extended the cease-fire indefinitely in late 2008 and also ordered most members of the milita to disarm. Politically, however, his party remained significant. In the 2010 parliamentary elections it was the principal component of the National Iraqi Alliance, a Shiite coalition led by Ibrahim al-Jaafari that included most of the main parties in the former United Iraqi Alliance, and the party joined the government formed in late 2010. Sadr is believed to have spent most of 2007–2010 at Qom, Iran, having fled Iraq in 2006 or 2007; he publicly returned to Iraq in early 2011, but has since spent time in Iran. In 2014, amid the successes in N Iraq of the Sunni militia the Islamic State in Iraq and Syria, he revived the Mahdi Army as an independent Shiite force.

See biography by P. Cockburn (2008).