Mansur Abbasi
Abu Ja'far Abdallah ibn Muhammad Mansur (born: 714 AD; died: 775 AD, was the second Abbasid Caliph from 754 – 775. Al-Mansur was concerned with the solidity of his regime after the death of his brother, Abu'l `Abbas, who later become known as-Saffah (the bloodshedder). In 755 he arranged the assassination of Abu Muslim. Abu Muslim was a loyal freed man from the eastern Iranian province of Khorasan who had led the Abbasid forces to victory over the Umayyads during the Third Islamic Civil War in 749-750. At the time of al-Mansur he was the ####subordinate, but undisputed ruler of Iran and Transoxiana. The assassination seems to have been made to preclude a power struggle in the empire. He deposed Isa bin Musa bin Muhammad bin Ali as his successor and in his place appointed al-Mahdi as his successor and took public allegiance for him. He was a miserly person and there are many events related to his evil attribute and for his evil-habit he became famous as Dawaniqi and thus was called Mansur Dawaniqi. Mansur crushed the uprising of Sanbad in the year 138 A.H., revolt of Astazsis in the year 151 A.H. and movement of al-Muqannah in the year 163 A.H. Al-Mansur many times imprisoned Imam Jafar Sadiq (P.B.U.H) and martryed the Sixth Holy Imam by poisoning in the year 148 A.H. He killed a large number of Shi'ites Mansur was the first person to destroy the holy shrine of Imam Husain (P.B.U.H) at Karbala (Iraq). Mansur was a gluttonous person and died due to excessive eating in the year 775 A.D. During his reign, literature and scholarly work in the Islamic world began to emerge in full force, supported by new Abbasid tolerances for Persians and other groups suppressed by the Umayyads. A very impressive aspect of this caliph's character is that when he died he left in the treasury six hundred thousand dirhams and fourteen million dinars.
Sources :
wikipedia