The Thirteenth Infallible, The Eleventh Imam
Al-Hasan Ibn Ali Al-Askari (Peace be on him)

Name: Al-Hasan.
Title: Al-Askari.
Agnomen*: Abu Muhammad.
Father's name: `Ali al-Hadi (an-Naqi).
Mother's name: Hadithah (or Susan).
Birth: In Medina, on Friday, 8th Rabi`u'thani, 232 AH.
Death: Died at the age of 28, in Samarra', on Friday, 8th of Rabi`ul-awwal 260 AH; poisoned by al-Mu'tamid, the Abbasid ruler; buried in Samarra' (Iraq).

The Holy Imam Hasan al-Askari (a.s.) spent twenty-two years of his life under the patronage of his father, Imam Ali al-Hadi (an-Naqi) after whose martyrdom he became his divinely commissioned Imam.

Imam Hasan ibn Ali al-Askari, the son of the Tenth Imam, was born in 232/845 and according to some Shii'te sources was poisoned and killed in 260/872 through the instigation of the Abbasid caliph al-Mu'tamid. The Eleventh Imam gained the Imamate, after the death of his noble father, through Divine Command and through the decree of the previous Imams. During the seven years of his Imamate, due to untold restrictions placed upon him by the caliphate, he lived in hiding and dissimulation (taqiyyah). He did not have any social contact with even the common people among the Shi`ite population. Only the elite** of the Shi'ah were able to see him. Even so, he spent most of his time in prison.

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*Also known as, or his Alias.
** A reference to those chosen by the Imam (a.s.) himself due to their high rank as scholars and protectors of the faith.