Māshāʾallāh ibn Atharī (Persian: ماشاءالله ابن اثری یهودی; c. 740 – 815), known as Mashallah, was an 8th-century Persian Jewish astrologer, astronomer, and mathematician. Originally from Khorasan, he lived in Basra (in present-day Iraq) during the reigns of the Abbasid caliphs al-Manṣūr and al-Ma’mūn, and was among those who introduced astrology and astronomy to Baghdad. The bibliographer ibn al-Nadim described Mashallah "as virtuous and in his time a leader in the science of jurisprudence, i.e. the science of judgments of the stars". Mashallah served as a court astrologer for the Abbasid caliphate and wrote works on astrology in Arabic. Some Latin translations survive.
The Arabic phrase mā shā’ Allāh indicates a believer's acceptance of God's ordainment of good or ill fortune. His name is probably an Arabic rendering of the Hebrew Shiluh. Al-Nadim writes Mashallah's name as Mīshā ("Yithru" or "Jethro").
