Iranian economist and politician who in 1980 was elected the first president of the Islamic Republic of Iran. He was dismissed from office in 1981 after being impeached for incompetence.

Bani-Sadr studied religion and economics at the University of Tehrān and spent four years at the Institute of Social Research. He was leader of the anti-shah student movement in the early 1960s and was imprisoned twice for political activities. Wounded in the unsuccessful uprising of June 1963, he traveled to France and continued his studies at the Sorbonne in Paris, where he obtained a doctorate and later taught. A fervent Islamic nationalist and revolutionary economist, he published the results of his studies in the 1970s.

Bani-Sadr joined Ayatollah Ruhollah Khomeini (Khomeini, Ruhollah)'s entourage during the latter's exile in France. After civil unrest forced the shah to flee Iran, the two men returned to the country on February 1, 1979. Khomeini assumed control of the country and appointed a government, naming Bani-Sadr deputy minister of economy and finance in July and full minister in November. On January 25, 1980, Bani-Sadr was elected the first president of the Islamic Republic of Iran, and the following month Khomeini appointed him chairman of the Revolutionary Council, Iran's policy-making body.

As president, Bani-Sadr struggled against enemies in the clergy, such as Ali Akbar Hashemi Rafsanjani (Rafsanjani, Hashemi) and Ali Khamenei (Khamenei, Ali)—who sought to reduce him to a figurehead—and against inexperienced departmental executives. He was forced to accept Mohammad Ali Rajaʾi (Rajaʾi, Mohammad Ali), not a man of his choice, as prime minister in August. The two men were soon at odds as Bani-Sadr refused to accept many of the prime minister's cabinet nominations. Then in September, Iraq invaded Iran, sparking the Iran-Iraq War (1980–88). On October 31, Bani-Sadr wrote a letter to Khomeini complaining that incompetent ministers were a greater danger to the country's security than was Iraqi aggression. He also noted in this missive that his warnings of a worsening economy and his insistence on the need to reorganize the armed forces were being ignored. The letter, as well as Bani-Sadr's opposition to Iran's holding American hostages taken from the U.S. embassy in Tehrān some time earlier, angered members of the Majles (parliament), who impeached him on June 21, 1981. The following day Khomeini—angered further by Bani-Sadr's negotiations with the Mojāhedīn-e Khalq (Persian: “People's Fighters”), an antigovernment group—dismissed him as president and ordered his arrest on charges of conspiracy and treason. Bani-Sadr fled to France, where—along with Mojāhedīn-e Khalq leader Massoud Rajavi—he helped establish the National Council of Resistance, a group dedicated to overthrowing the Khomeini regime. In 1984 Bani-Sadr left the coalition because of a dispute with Rajavi.