Son of Ali (his mother Umm al-Banin) and half-brother of Hasan and Husayn. At Karbala he was the standard-bearer of Husayn's army and fetched water; martyred on 10 Muharram 61 AH (680). His shrine is near Husayn's, linked by the Bayn al-Haramayn plaza. (Sources: TDV 'Abbas b. Ali'; WikiShia.)