Ali al Hadi
Al ibn Muhammad ibn Al commonly called Ali alHadi and Al anNaq was known as alHadi. He was the tenth of the Twelve Imams after his father Muhammad alJawad and before his son Hasan alAskari. He remained in Medina teaching until the age ofwhen he was summoned to Samarra by the Abbasid caliph AlMutawakkil. There he was treated roughly by the caliph and his successors until, according to Shiite accounts, he was poisoned through intrigue of AlMutazz the Abbasid caliph, in 254868, and was buried in Samarra.
According to the most accurate reports he was born in 828 in a village near Medina called Sorayya. to the ninth Shiite Imm, Muhammad alTaqi, , and Lady Samnah or Susan, who was originally a Berber . His father bestowed upon him the surname AbulHasan, after the surnames given to his grandfather Ali alRidha and his great grandfather Musa alKadhim. To differentiate between these three Abul Hasan, narrators usually call Musa alKadhim, abul Hasan the first, call Ali alRidha, Abul Hasan the second and call alHadi Abul Hasan the third.
Source: Wikipedia