Al-Amir bi-Ahkam Allah

Names
	Abū ʿAlī al-Manṣūr ibn al-Mustaʿlī

al-Amir bi-Ahkam Allah
al-Amir bi-Ahkam Allah
	Gold dinar of al-Amir, minted in Cairo, 514 AH (1119/20 CE)
Imam–Caliph of the Fatimid Caliphate
Reign	1101–1130
Predecessor	al-Musta'li
Successor	al-Hafiz (as caliph and Hafizi imam); al-Tayyib (as Tayyibi imam);
Born	31 December 1096; Cairo, Fatimid Caliphate (present-day Egypt)
Died	7 October 1130 (aged 33); Cairo, Fatimid Caliphate (present-day Egypt)
Issue	al-Tayyib
Names
Names
	Abū ʿAlī al-Manṣūr ibn al-Mustaʿlī
Dynasty	Fatimid
Father	al-Musta'li

Abu Ali al-Mansur ibn al-Musta'li (Arabic: أبو علي المنصور بن المستعلي, romanized: Abū ʿAlī al-Manṣūr ibn al-Mustaʿlī; 31 December 1096 – 7 October 1130), better known by his regnal name al-Amir bi-Ahkam Allah (Arabic: الآمر بأحكام الله, romanized: al-Āmir bi-Aḥkām Allāh, lit. 'The Ruler Who Executes God's Decrees') was the tenth Fatimid caliph, ruling from 1101 to his death in 1130, and the 20th imam of the Musta'li Isma'ili branch of Shia Islam.

Until 1121, he was a de facto puppet of his uncle and father-in-law, the vizier al-Afdal Shahanshah. When the latter was murdered, possibly with al-Amir's connivance, he appointed al-Ma'mun al-Bata'ihi as his vizier, but took an increasing direct role in government, and after 1125 ruled without a vizier. His reign saw the progressive loss of all Fatimid strongholds in Palestine to the Crusaders, apart from Ascalon. His assassination in 1130, leaving only his infant son al-Tayyib as heir, threw the Fatimid regime into a succession struggle during which it almost collapsed. Fatimid rule was restored with the succession of al-Amir's cousin al-Hafiz li-Din Allah in 1132, which led to the division of Musta'li Isma'ilism into the rival Hafizi and Tayyibi branches.