Abū Muḥammad ʿAbd Allāh ibn al-Ḥusayn, better known by his regnal name al-Mahdī biʾllāh, was the founder of the Isma'ili Fatimid Caliphate, the only major Shi'a caliphate in Islamic history, and the eleventh Imam of the Isma'ili branch of Shi'ism.
- Occupation
- politician, imam, caliph
- Position held
- Fatimid Caliph, Ismaili imam
- Born
- 873
- Died
- 934
