Abū ʿAbd Allāh Muḥammad ibn ʿAbd Allāh al-Manṣūr (Arabic: أبو عبد الله محمد بن عبد الله المنصور; 744 or 745 – 785), better known by his regnal name Al-Mahdī (المهدي, "He who is guided by God"), was the third Abbasid Caliph who reigned from 775 to his death in 785. He succeeded his father, al-Mansur.