Yūḥannā ibn Māsawayh, despite being a renowned ophthalmologist, pharmacist, and translator from the Islamic period, is a figure shrouded in debate and ambiguity among scholars due to contradictory historical reports and uncertainties surrounding his attributed works. Catalogers have noted numerous medical works in his name. Yūḥannā served as a key reference for doctors and pharmacists of the era, with notable scientists like Abū Rayhān al-Bīrūnī, Muhammad ibn Zakariyyā al-Rāzī, Ibn al-Jazzar, Ibn al-Bayṭār and Hubaysh-i Tiflisi frequently quoting and referencing his works in their books including Al-Saydanah, Al-Hawi, Al-Iʿtimād, Al-Jāmi li-Mufradāt al-Adwiya and Kifāyat al-Tibb. Remarkably, his fame extends beyond the Islamic world. The attribution of three influential medieval pharmaceutical treatises to an unknown individual named “Mesue” likely inspired by Yūḥannā ibn Māsawayh's name—showcases the global recognition of this Islamic period scholar, regardless of the correctness of the attribution of these treatises.