Muhammad ibn Hasan al-Mahdī (Arabic: محمد بن الحسن المهدي) is believed by Twelver Shī‘a Muslims to be the Mahdī, an ultimate savior of humankind and the final Imām of the Twelve Imams who will emerge with Isa (Jesus Christ) in order to fulfill their mission of bringing peace and justice to the world. Twelver Shī‘a believe that al-Mahdī was born in 869 (15 Sha‘bān 255 AH) and assumed Imamate at 5 years of age following the death of his father Hasan al-Askari.