Al-Mutawakkil Ahmad bin Sulayman (1106–1171) was an imam of the Zaidi state in Yemen who revived the polity after a long interregnum, wielding power in 1138–1171.
Since the violent death of al-Muhtasib al-Mujahid Hamzah in 1066, no new imam had been appointed in the Zaydiyyah community of the northern Yemeni highlands.
The dominating political power in Yemen in the late 11th and early 12th centuries was the Ismailite Sulayhids, whose last important representative was Queen Arwa al-Sulayhi (d. 1138).
In 1151 a large congregation gathered and spent eight days testing his qualifications for the imamate, including physical fitness, right descent, religious doctrinal learning, etc.
Al-Mutawakkil Ahmad acknowledged the Shi'ite branch of the Mu'tazila school of theology, which originated from Basra and Baghdad in the eight and ninth centuries and stressed reason and rational thought, as a close ally.
In the beginning of his reign, the Zaidi positions were pushed back by the sultan of San'a, Hamid ad-Dawlah Hatim.
Hamid ad-Dawlah was unable to withstand the tribesmen who supported al-Mutawakkil Ahmad, and was defeated in battle near San'a.
From his base in the mountains adjoining the northern Tihamah, their leader Ali bin Mahdi attacked the lowland.