Hassan-i Sabbāh (
Persian: حسن صباح
Hasan-e Sabbāh) or
Hassan al-Sabbāh (
Arabic: حسن الصباح
Ḥasan aṣ-Ṣabbāḥ) (1050s-1124) was a
Nizārī Ismā‘īlī missionary who converted a community in the late 11th century in the heart of the
Alborz Mountains of northern
Persia. He later seized a mountain fortress called
Alamut and used it as the headquarters for a decentralized Persian insurrection against the dominant
Seljuk Turks. He founded a group of
fedayeen whose members are often referred to as the
Hashshashin, or "Assassins".