Muÿën al-Dën Ḥasan ibn al-Shaykh (died 10/12 February 1246) was the vizier of the Ayyubid sultan of Egypt, al-á¹¢ÃÂliḥ Ayyà «b, from 1240 until his death.
Muÿën al-Dën belonged to a family known as the AwlÃÂd al-Shaykh. His ancestors came from KhorÃÂsÃÂn. He was the youngest of four brothers. His elder brothers were Fakhr al-Dën Yà «suf, ÿImÃÂd al-Dën ÿUmar and KamÃÂl al-Dën Aḥmad. Like his brothers, he was a á¹£à «fë who taught ShÃÂfiÿë jurisprudence in Cairo before entering politics.
Muÿën al-Dën was appointed "deputy of the vizier" (nÃÂþib al-wizÃÂra) by Sultan al-KÃÂmil. He was part of the council that, after al-KÃÂmil's death in 1240, elected al-JawwÃÂd Yà «nus as regent in Damascus. He was promoted to full vizier by al-KÃÂmil's successor, al-á¹¢ÃÂliḥ Ayyà «b, that same year. In 1243, he was part of the attempted rapprochement between the sultan and the Ayyubid emirs in Syria and the alliance with the KhwÃÂrazmians that caused its collapse. After the EgyptianâÂÂKhwÃÂrazmian victory over the Franks and Syrians at the battle of La Forbie in 1244, al-á¹¢ÃÂliḥ Ayyà «b, who had remained in Cairo, put Muÿën al-Dën in command of the army and sent it to capture Damascus.
For the 1245 campaign, Muÿën al-Dën was granted plenary powers, including the rights to use the royal pavilion (al-dihlëz al-sulá¹ÂÃÂnë) and be served by the royal staff. He joined the KhwÃÂrazmian army at Gaza and led the combined force to BaysÃÂn and thence to Damascus. The siege of Damascus began in May and lasted over four months. Negotiations for a surrender were conducted by Muÿën al-Dën and Amën al-Dawla, vizier of Damascus. It was agreed that al-á¹¢ÃÂliḥ IsmÃÂÿël would surrender Damascus but retain Baÿlabakk and his ally, al-Maná¹£à «r IbrÃÂhëm, would retain Ḥimá¹£. Both received a safeconduct and Muÿën al-Dën entered Damascus on 2 October. Shortly after, he received a belated order to detain al-á¹¢ÃÂliḥ IsmÃÂÿël.
After its conquest, Muÿën al-Dën governed Damascus as al-á¹¢ÃÂliḥ Ayyà «b's viceroy (nÃÂþib al-salá¹Âana). He distributed iqá¹ÂÃÂÿs (lands) to the KhwÃÂrazmains, but they considered them insufficient. He appointed ShihÃÂb al-Dën Rashëd al-Kabër as governor of the citadel (wÃÂlë al-qalÿa) and JamÃÂl al-Dën HÃÂrà «n as governor of the holy places (wÃÂlë al-madëna). He also replaced al-á¹¢ÃÂliḥ IsmÃÂÿël's qÃÂá¸Âë with one of his own men.
Al-á¹¢ÃÂliḥ Ayyà «b appointed ḤusÃÂm al-Dën ibn Abë ÿÃÂlë as governor of Damascus to replace Muÿën al-Dën, who died of typhoid in February 1246, shortly after ḤusÃÂm al-Dën's arrival.