Imam (; Arabic: إمام imām; plural: أئمة aʼimmah) is an Islamic leadership position. For Sunni Muslims, Imam is most commonly used as the title of a worship leader of a mosque. In this context, imams may lead Islamic worship services, lead prayers, serve as community leaders, and provide religious guidance. Thus for Sunnis, anyone can study the basic Islamic sciences and become an Imam.

For most Shia Muslims, the Imams are absolute infallible leaders of the Islamic community after the Prophet. Shias consider the term to be only applicable to the members and descendents of the Ahl al-Bayt, the family of the Islamic prophet Muhammad. In Twelver Shīʿīsm there are 14 infallibles, 12 of which are Imams, the final being Imam Mahdi who will return at the end of times. The title was also used by the Zaidi Shia Imams of Yemen, who eventually founded the Mutawakkilite Kingdom of Yemen (1918–1970).