Abū Muḥammad ʿAbd Allāh ibn Yūsuf ibn al-Ḥāfiẓ, better known by his regnal name al-ʿĀḍid li-Dīn Allāh, was the fourteenth and last caliph of the Fatimid dynasty, and the twenty-fourth imam of the Hafizi Isma'ili branch of Shi'a Islam, reigning from 1160 to 1171.

The Fatimid dynasty was an Arab dynasty that ruled the Fatimid Caliphate, between 909 and 1171 CE. Descended from Fatima and Ali, and adhering to Isma'ili Shi'ism, they held the Isma'ili imamate, and were regarded as the rightful leaders of the Muslim community. The line of Nizari Isma'ili imams, represented today by the Aga Khans, claims descent from a branch of the Fatimids. The Alavi Bohras, predominantly based in Vadodara, also claim descent from the Fatimids.