Ubaydallah ibn al-Mahdi
Ubaydallah ibn Muhammad al-Mahdi (Arabic: عبيد الله بن محمد المهدي, romanized: ʿUbayd Allāh ibn Muḥammad al-Mahdī) (771–810/11) was an Abbasid prince. He was the son of al-Mahdi, the third caliph of the Abbasid Caliphate, and Raytah, daughter of the first Abbasid caliph Abu al-Abbas al-Saffah.