Ali ibn Abi talib (c.598-661 CE). The son of Abu Talib, Ali was also the cousin and son-in-law of the Prophet, Muhammad, ruling over the Islamic Caliphate from 656 to 661, and was the first male convert to Islam. Sunnis consider Ali the fourth and final of the Rashidun (rightly guided) Caliphs, while Shia regard Ali as the first Imam and consider him and his descendants the rightful successors to Muhammad, all of which are members of the Ahl al-Bayt, the household of Muhammad. This disagreement split the Ummah (Muslim community) into the Sunni and Shia branches.