Abu'l-Abbas ibn al-Muwaffaq

Al-Mu'tadid bi-llah المعتضد بالله
Gold dinar of al-Mu'tadid, AH 285 (AD 892/3)
16th Caliph of the Abbasid Caliphate
Reign	15 October 892 – 5 April 902
Predecessor	al-Mu'tamid
Successor	al-Muktafi
Born	ca. 854 or ca. 861
Died	5 April 902 (aged 48 or 41) Baghdad
Burial	Baghdad
Consort	Qatr al-Nada bint Khumarawayh, Shaghab
Issue	al-Muktafi al-Muqtadir al-Qahir
Father	al-Muwaffaq
Mother	Dirar
Religion	Sunni Islam

Abu'l-Abbas Ahmad ibn Talha al-Muwaffaq (854 or 861 – 5 April 902), better known by his regnal name al-Mu'tadid bi-llah (Arabic: المعتضد بالله‎‎, "Seeking Support in God") was the Abbasid Caliph in Baghdad from 892 until his death in 902.

Al-Mu'tadid was the son of al-Muwaffaq, who was the regent and virtual ruler of the Abbasid state during the reign of his brother, Caliph al-Mu'tamid. As a prince, the future al-Mu'tadid served under his father in various military campaigns, most notably in the suppression of the Zanj Rebellion, in which he played a major role. When al-Muwaffaq died in June 891 al-Mu'tadid succeeded him as regent. He quickly sidelined his cousin and heir-apparent al-Mufawwad, and when al-Mu'tamid died in October 892, he succeeded to the throne. Like his father, al-Mu'tadid's power depended on his close relations with the army, first forged in the campaigns against the Zanj and reinforced in later expeditions which the Caliph led in person: al-Mu'tadid would prove to be the most militarily active of all Abbasid caliphs. Through his energy and ability, he succeeded in restoring to the Abbasid state some of the power and provinces it had lost during the turmoils of the previous decades.

In a series of campaigns he recovered the provinces of Jazira, Thughur and Jibal, and effected a rapprochement with the Saffarids in the east and the Tulunids in the west that secured their—albeit largely nominal—recognition of caliphal suzerainty. These successes came at the cost of gearing the economy almost exclusively towards maintenance of the army, which resulted in the expansion and rise to power of the central fiscal bureaucracy and contributed to the Caliph's lasting reputation for avarice. Al-Mu'tadid was also renowned for his cruelty when punishing criminals, and subsequent chroniclers record his extensive and ingenious use of torture. His reign also saw the permanent move of the capital back to Baghdad, where he engaged in major building activities. A firm supporter of Sunni traditionalist orthodoxy, he nevertheless maintained good relations with the Alids, and was interested in natural sciences, renewing caliphal sponsorship of scholars and scientists.