Rashid ad-Din Sinan

Rashid al-Din Sinan also known as the Old Man of the Mountain, was an Arab Muslim missionary who served as the leader of the Nizari Ismaili state and the Order of Assassins from 1162 until his death in 1193. An adherent of Nizari Ismailism, a branch of Shia Islam, he was a prominent figure during the Crusades.