Al-Mu'ayyad fid-din Abu Nasr Hibat Allah b. Abi 'Imran Musa b. Da'ud ash-Shirazi (c. 1000 CE/390 AH – 1078 CE/470 AH) was an 11th-century Isma'ili scholar, philosopher-poet, preacher and theologian of Persian origin. He served the Fatimid Caliph-Imām al-Mustansir Billah as a Da'i in varying capacities, eventually attaining the highest rank of Bab al-Abwab "The Gate of Gates" and Da'i al-du'at "Chief Missionary" in the Fatimid Da‘wah. In his theological and philosophical writings he brought the Isma'ili spiritual heritage to its pinnacle.