‘Alā’ ad-Dīn Muḥammad III

ʿAlāʾ ad-Dīn Muḥammad III (1211–1255), also known as Aladdin, son of Jalāl al-Dīn Ḥassan III, was the 26th Nizāri Ismāʿilī Imām. He ruled from 1221-55. His reign witnessed the beginnings of the Mongol devastations of Persia and the eastern Muslim world, and he tried unsuccessfully to establish friendly ties with the Mongols and to prevent their destruction of the Nizari state, which was already underway.
He was succeeded by his eldest son Rukn al-Din Khurshah in 1255.

He was the only surviving son of Jalaluddin Hasan, whom he succeeded at the age of 9 years old, in 1221. However, upon succession he was initially too young, so Ḥassan III's vizier controlled the state. His mother was a Sunni women and a daughter of one of the princes of Gilan.

Under Muhammad III's reign, the Sunni conformity initiated by his father was gradually and quietly reversed and his community increasingly regarded itself openly as Ismaili Shi'ite.

His rule was described as "cruel, imperious, sadistic, alcoholic, and unpredictable."

Muhammad III was murdered in 1255 by Hasan Mazandarani. Mazandarani and three of his children were later executed by the succeeding Imam, Khurshah, as retribution. Muhammad III's murder prevented the need to implement a plan, which was hatched by Nizari leaders (concerned about the Imam's alarming mental deterioration), to replace him with Khurshah.