The Guardian Council of the Constitution (Persian: شورای نگهبان قانون اساسی‎, Shora-ye Negahban-e Qanun-e Assassi), also known as the Guardian Council or Council of Guardians, is an appointed and constitutionally-mandated 12-member council that wields considerable power and influence in the Islamic Republic of Iran.

The Iranian constitution calls for the council to be composed of six Islamic faqihs (expert in Islamic Law), "conscious of the present needs and the issues of the day" to be selected by the Supreme Leader of Iran, and six jurists, "specializing in different areas of law, to be elected by the Majlis (the Iranian Parliament) from among the Muslim jurists nominated by the Head of the Judicial Power," (who, in turn, is also appointed by the supreme leader).

It is charged with interpreting the Constitution of Iran, supervising elections of, and approving of candidates to, the Assembly of Experts, the President and the Majlis, and "ensuring ... the compatibility of the legislation passed by the Islamic Consultative Assembly [i.e. Majlis] ... with the criteria of Islam and the Constitution", i.e., as the watchdog of the constitution it can veto any law passed by the Majlis.

Massoud Rajavi (Persian: مسعود رجوی‎, born 18 August 1948), is the president of the National Council of Resistance of Iran and the leader of People's Mujahedin of Iran (PMOI, also known as the MEK), an opposition organization active inside and outside of Iran. After leaving Iran in 1981, he resided in France and Iraq. Since the 2003 invasion of Iraq, he has not made any public appearances, although it is believed he has sent several audio messages to his followers. The last of these messages was sent on 22 August 2011 congratulating the overthrow of Gaddafi in Libya and the great victory of the people.

Massoud Rajavi is a graduate of political law from Tehran University. He joined the PMOI when he was 20 and a law student at Tehran University. Later on he was arrested by SAVAK (the Shah's secret police) and was sentenced to death. Due to efforts by his brother Prof. Kazem Rajavi, Amnesty International, the International Committee of the Red Cross, as well as distinguished European personalities such as François Mitterrand, he was not executed and remained in prison until released by the people during the revolution in 1979. His death sentence was commuted as a result of international pressure. Prof. Kazem Rajavi was assassinated in April 1990 in Geneva by agents of the Iranian Islamic regime. Massoud Rajavi was released from prison three weeks before the revolution in February 1979. Upon his release, Rajavi assumed leadership of the Islamic MEK, reclaiming the name from the Marxists. This was the beginning of the MEK as it exists today. Rajavi and the MEK actively opposed the Shah of Iran and participated in the 1979 Iranian Revolution.