Hakim bi-Amr Allah, Caliph of Egypt, 985-approximately 1021

Abu Ali al-Mansur (Arabic: أبو علي المنصور, romanized: Abū ʿAlī al-Manṣūr; 13 August 985 – 13 February 1021), better known by his regnal name al-Hakim bi-Amr Allah (Arabic: الحاكم بأمر الله, romanized: al-Ḥākim bi-Amr Allāh, lit. 'The Ruler by the Order of God'), was the sixth Fatimid caliph and 16th Ismaili imam (996–1021). Al-Hakim is an important figure in a number of Shia Ismaili sects, such as the world's 15 million Nizaris and 1–2 million Musta'lis, in addition to 2 million Druze. Histories of al-Hakim can prove controversial, as diverse views of his life and legacy exist. Historian Paul Walker writes "Ultimately, both views of him, the mad and despotic tyrant (like Germanic and Roman despots) irrationally given to killing those around him on a whim, and the ideal supreme ruler, divinely ordained and chosen, whose every action was just and righteous, were to persist, the one among his enemies and those who rebelled against him, and the other in the hearts of true believers, who, while perhaps perplexed by events, nonetheless remained avidly loyal to him to the end." Appraisals of the more controversial accounts of al-Hakim's life and rule have earned him such monikers as "the Nero of Egypt", and "the Mad Caliph".