Muḥammad ibn al-Ḥasan al-Mahdī (Arabic:محمد بن ا…ن المهدي) (born c. July 29, 869 (15 Sha‘bān 255 AH), in Occultation since 874) is believed by Twelver Shī‘a Muslims to be the Mahdī, an ultimate savior of humankind and the final Imām of the Twelve Imams. Twelver Shī‘a believe that al-Mahdī was born in 869 and did not die but rather was hidden by God in 941 (this is referred to as the Occultation) and will later emerge with Isa (Jesus Christ) in order to fulfill their mission of bringing peace and justice to the world. He assumed the Imamate at 5 years of age. Some Shi‘īte schools do not consider ibn-al-Hasan to be the Mahdī, although the majority sect Twelvers do.
In Islamic eschatology, the Mahdi (Arabic: مهدي / ISO 233: mahdī / English: Guided One) is the prophesied redeemer of Islam who will rule for seven, nine or nineteen years- (according to various interpretations) before the Day of Judgment (yawm al-qiyamah / literally, the Day of Resurrection) and will rid the world of evil.