Ubaydallah ibn Muhammad al-Mahdi (Arabic: عبيد الله بن محمد المهدي‎)[1] (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.[2]