Al-Musta'li

Abūl-Qāsim ’Ahmad al-Mustā‘lī bil-Lāh (16 September 1074 – 12 December 1101), (Arabic: أبو القاسم أحمد المستعلي بالله‎) was the ninth Fatimid Caliph, and believed by the Mustaali Ismaili sect to be the 19th imam. Al-Musta‘li was made caliph by the vizier Malik al-Afdal Shahanshah and was the successor to al-Mustansir. By and large, al-Musta‘li was subordinate to Malik al-Afdal. One complication with the selection of al-Musta‘li was that his older brother Nizar was considered by Nizar's supporters to be the rightful heir to the throne. This led to a power struggle within the Fatimids, and although Nizar's revolt was unsuccessful (ending with his death in prison in 1097), the break from the rules of succession caused a schism among the Ismaili Shia. In Seljuk Syria and Persia, the Nizari sect developed, one branch of which is known to history as the Hashshashin. Supporters of Musta'li's imamate became known as the Mustaali sect.

During al-Musta‘li's reign, the First Crusade (1099) established the Kingdom of Jerusalem, the County of Tripoli and the Principality of Antioch, which further reduced Fatimid power in Syria and Palestine. He was succeeded by his son Al-Amir (r. 1101–1130), after whose reign the Mustaali sect again split into the Hafizi and Taiyabi sects.