The son of the 4th caliph Ali and Fatima, daughter of Muhammad. Shiites regard him as the 2nd Imam after Ali.
al Hasan died in Medina of poision. His wife Jadah, daughter of al Ashath b Kays poisioned him. Yazid b, Muawiyah suborned her to poision him, promising that he would then marry her, and she did so. And when al Hasan was dead, she went to Yazid claiming the fulfillment of what he had promised, but he replied: I did not approve thee for al Hasan, shall I be content with thee for myself? (al-Suyuti, Tarikhul Khulafa, Chapter: al Hasan b. Ali b. Abi Talib, p. 195)