Muslim Arab dynasty that ruled central Iraq from its capital at al-Ḥillah in the period from about 961 to 1150. The Mazyad family, which belonged to the Bedouin tribe of Asad, had settled along the Euphrates River, between Hīt and Kūfah, in the middle of the 10th century; soon afterward the Būyid Sulṭān ad-Dawlah in Baghdad recognized ʿAlī I ibn Mazyad as emir of the area. ʿAlī died in 1018, leaving behind three sons, each of whom was eager to assume power, although Dubays I (reigned 1018–81) officially succeeded his father. Dubays' brother al-Muqallad soon attempted to oust him but, failing, turned to the ʿUqaylid capital of Mosul for help. In 1030, supported by ʿUqaylid and Būyid forces, al-Muqallad routed Dubays. Dubays, however, was allowed to return to his capital, provided that he pay a sizable tribute to the Būyid Jalāl ad-Dawlah. Meanwhile, the third brother, Thābit, enlisted the aid of Arslān al-Basāsīrī of Baghdad in his bid for power and defeated Dubays twice in about 1033, forcing him to relinquish parts of the province to him. About 1057 Dubays himself allied with al-Basāsīrī against an invasion by the Seljuqs (Seljuq) under Toghrïl Beg.

The brief rule of Manṣūr (1081–86) was followed by a period of heightened Mazyadid activity. Having allied himself first with the Seljuq ruler Berk-yaruq, then from about 1101 with Berk-yaruq's brother Muḥammad, the Mazyadid ruler Ṣadaqah I (reigned 1086–1108) gradually assumed control of most of Iraq, seizing Hīt, Wāsiṭ, Basra, and Takrīt. In 1102 he expanded and fortified his capital city of al-Jāmiʿān and renamed it al-Ḥillah. Ṣadaqah, however, proved to be too threatening to Muḥammad, and the Mazyadid ruler was killed in a battle with Seljuq armies sent out against him early in 1108.

Dubays II (reigned 1108–35) succeeded to the throne on his father's death and distinguished himself as a great warrior against the crusaders and as a generous patron of Arabic poetry. After Dubays' death, Mazyadid strength was reduced by his three brothers' efforts to displace one another from power. The dynasty finally submitted to the Seljuq sultan Masʿūd in 1150, and al-Ḥillah was given to one of the sultan's generals.