Abū Manṣūr Nizār al-Muṣṭafá li-Dīn’il-Lāh (1045-1097, ) was the founder (and an Imām) of the Nizāri branch of Ismā‘ilī Shia Islam. Following the death of his father, Al-Mustansir Billah, he was deposed by his brother,  Ahmad al-Musta‘lī but his son, al-Hādī ibn Nizār, escaped to Alamūt and took refuge with believers there, thereby continuing the Imāmate.