Nizar ibn al-Mustansir

Nizar ibn al-Mustansir was a prince of the Fatimid dynasty, the Cairo-based Shia Ismaili caliphate that then ruled Egypt. He was the eldest son of al-Mustansir, who held the joint office of caliph (political ruler) and imam (spiritual leader). Reliable sources report that al-Mustansir at one point designated Nizar his heir through nass, the formal naming of a successor that Ismaili doctrine regards as binding.

When al-Mustansir died at the end of 1094, the powerful army commander and vizier (chief minister) al-Afdal Shahanshah instead installed Nizar's younger half-brother, who took the throne as al-Musta'li. Nizar fled to the port of Alexandria, where the governor and townspeople backed him; he proclaimed himself caliph under the regnal title al-Mustafa li-Din Allah ("the Chosen for God's Religion"), a claim confirmed by a gold coin found in 1994. His revolt failed: he was besieged, surrendered, was carried back to Cairo, and there killed by being walled up alive (immurement), reportedly in 1095.

Whether the designation of Nizar or of al-Musta'li was the valid one is a matter on which Ismailis themselves divide, and this site does not adjudicate it. The dispute produced a permanent split: Ismailis who upheld Nizar's claim became the Nizari branch, whose imamate is traced by tradition through his line down to the Aga Khans. Those who recognized al-Musta'li formed the Musta'li branch.