Muḥammad ibn Buzurg-Ummëd (; died February 20, 1162) was the son of KiyàBuzurg-Ummëd, and the third ruler of the Nizari Ismailis from 1138 until 1162 based in Alamut.
Upon the demise of KiyàBuzurg-Ummëd on February 9, 1138, he was appointed as the commander of Alamut Castle by the third concealed Imam Hasan Al-QÃÂhir ibn Al-Muḥammad (çÃÂÃÂçÃÂñ) of the NizÃÂrë IsmÃÂ'ëlë state. He died in 1162 and was succeeded by his son Hassan as dai. Some, including authoritative (though biased) historian Joveyni, claim that it was his son who declared himself imam as Hasan âÂÂAlàDhëkrâÂÂëhë's-SalÃÂm, de facto usurping the Nizari Imamate. Nizari sources generally claim that the two individuals are distinct.