Abu Abdallah al-Shi'i
Abu Abdallah al-Husayn ibn Ahmad ibn Zakariyya al-Shi'i (Arabic: ابو عبد الله الشيعي, Abū ʿAbd Allāh ash-Shi'ī; died 28 February 911) was a Da'i for the Isma'ilis in Yemen and North Africa, mainly active among the Kutama Berbers, whose teachings and conquest of Ifriqiya gave rise to the Fatimid Caliphate.
He was born in Kufa in Iraq (or Sanaa, according to some accounts) and was active in the administration of the Abbasid Caliphate, before he began to associate with Ismaili teachers. At first he proselytised under the guidance of Ibn Hawshab in Yemen and Mecca.
During a pilgrimage to Mecca in 279 A.H./892 CE, he met some Kutama Berbers that boasted of their independence and autonomy from the Aghlabids. Abu 'Abdullah sensed a chance and decided to follow their invitation to the Maghrib, where he arrived in 280/893. After successfully preaching the Ismaili doctrine among the Sanhaja, he was able to form a powerful army consisting of Berber peasants. He began conquering the cities of Ifriqiya up to the point where he finally took over ar-Raqqada, the palace city of the Aghlabids near Kairuan, in 909.
All this had been done by him to prepare for the appearance of Abdullah al-Mahdi Billah, the imam-caliph of the Fatimids. Al-Mahdi was rescued from a prison in Sijilmasa (present-day Morocco) and proclaimed as caliph, ruling from the former residence of the Aghlabids.
Al-Shi'i had hoped that al-Mahdi would be a spiritual leader, and leave the administration of secular affairs to him, but he was soon disappointed. After being suspected of complicity in a revolt of Kutama leaders, he was put to death in 911.