Sharaf al-Dīn al-Muẓaffar ibn Muḥammad ibn al-Muẓaffar al-Ṭūsī (died 1213/4) was a Persian mathematician and astronomer of the Islamic Golden Age (during the Middle Ages).
Tusi was born in Tus, Iran. He taught various mathematical topics including the science of numbers, astronomical tables and astrology, in Aleppo and Mosul. His best pupil was Kamal al-Din ibn Yunus. In turn Kamal al-Din ibn Yunus went on to teach Nasir al-Din al-Tusi, one of the most famous of all the Islamic scholars of the period. By this time Tusi seems to have acquired an outstanding reputation as a teacher of mathematics, for some travelled long distances hoping to become his students.