Al-usayn ibn Ali ibn Abi Talib (Arabic: ; 10 October 625 10 October 680) (his name is also transliterated as Husayn ibn 'Al, Husain, Hussain and Hussein), was a grandson of the Islamic prophet, Muhammad, and son of Ali ibn Abi Talib (the first Shia Imam and the fourth Rashid caliph of Sunni Islam) and Muhammad's daughter, Fatimah. He is an important figure in Islam as he was a member of the Bay (Arabic: , Household) of Muhammad and the Ahl al-Kis' (Arabic: , People of the Cloak), as well as the third Shia Imam.
Prior to his death, the Umayyad ruler Muawiya appointed his son Yazid as his successor in a clear violation of the Hasan-Muawiya treaty. When Muawiya died in 680 CE, Yazid demanded that Husain pledge allegiance to him. Husain was well-known as the grandson of Muhammad and was an exemplary Muslim; if Husain pledged allegiance to Yazid, who was corrupt, shameless, and tyrannical, it would be seen as legitimizing Yazid's behavior in Islam. Thus, in order to save Islam from Yazid's influence, Husain refused to pledge allegiance to Yazid, even though it meant sacrificing his life. As a consequence, he left Medina, his hometown, to take refuge in Mecca in AH 60. There, the people of Kufah sent letters to him, asking his help and pledging their allegiance to him. So he traveled towards Kufah; however, at a place near it known as Karbala, his caravan was intercepted by Yazid's army. He was killed and beheaded in the Battle of Karbala on 10 October 680 (the 10th of Muharram in 61 AH) by Shimr ibn Thil-Jawshan, along with most of his family and companions, including Husayn's six month old son, Ali al-Asghar, with the women and children taken as prisoners. Anger at Husayn's death was turned into a rallying cry that helped undermine the Umayyad caliphate's legitimacy, and ultimately overthrow it by the Abbasid Revolution.