He is based on a generic religious leader of the Islamic religion and the Muslim community who reside in Mosques.
Imams function similar to Monks but with better stats. In The Conquerors, Imams used the same sprite as Monks, but with The Forgotten they got their own unique sprite. They are also available in the Scenario Editor.
As a hero, the Imam cannot be converted and can regenerate health. Like other Monks, Imams are affected by all upgrades that affect Monks as well as any other bonuses that affect them.