Abu Ahmad Talha ibn Ja'far () (842 – June 2, 891), better known by his laqab as al-Muwaffaq bi-Allah (, "Blessed of God"), was an Abbasid prince and military leader, who acted as the virtual regent of the Abbasid Caliphate for most of the reign of his brother, Caliph al-Mu'tamid. His stabilization of the internal political scene after the decade-long "Anarchy at Samarra", his successful defence of Iraq against the Saffarids and the suppression of the Zanj Rebellion restored a measure of the Caliphate's former power and began a period of recovery, which culminated in the reign of al-Muwaffaq's own son, the Caliph al-Mu'tadid.