Al-Mustansir Billah, Fatimid caliph (d. 1094)
Abū Tamīm Ma‘ad al-Mustanṣir bi-llāh (Arabic: أبو تميم معد المستنصر بالله‎; July 2, 1029 – December 29, 1094/ January 6, 1095) was the eighth Fatimid Caliph from 1036 until 1094/95. He was one of the longest reigning Muslim rulers. His reign, otherwise mixed, was the twilight of the Fatimid state. The start of his reign saw the continuation of competent administrators running the Fatamid state (Anushtakin, al-Jarjara'i, and later al-Yazuri), overseeing the state's prosperity in the first two decades of al-Mustansir's reign. However, the break out of court infighting between the Turkish and Berber/Sudanese court factions following al-Yazuri's assassination, coinciding with natural disasters in Egypt and the gradual loss of administrative control over Fatamid possessions outside of Egypt, almost resulted in the total collapse of the Fatamid state in the 1060s, before the appointment of the Armenian general Badr al-Jamali, who assumed power as vizier in 1073, and became the de facto dictator of the country under the nominal rule of al-Mustansir.The caliph al-Mustanṣir bi-llāh was the last Imam before a disastrous split divided the Isma'ili movement in two, due to the struggle in the succession between al-Mustansir's older son, Nizar, and the younger al-Mustaʽli, who was raised to the throne by Badr's son and successor, al-Afdal Shahanshah. The followers of Nizar, who predominated in Iran and Syria, became the Nizari branch of Isma'ilism, while those of al-Musta'li became the Musta'li branch.