Ammonius Hermiae (/əˈmoʊniəs/; Ancient Greek: Ἀμμώνιος ὁ Ἑρμείου, romanized: Ammōnios ho Hermeiou, lit. 'Ammonius, son of Hermias'; c. 440 – between 517 and 526) was a Greek philosopher from Alexandria in the eastern Roman empire during Late Antiquity. A Neoplatonist, he was the son of the philosophers Hermias and Aedesia, the brother of Heliodorus of Alexandria and the grandson of Syrianus. Ammonius was a pupil of Proclus in Roman Athens, and taught at Alexandria for most of his life, having obtained a public chair in the 470s.
According to Olympiodorus of Thebes's Commentaries on Plato's Gorgias and Phaedo texts, Ammonius gave lectures on the works of Plato, Aristotle, and Porphyry of Tyre, and wrote commentaries on Aristotelian works and three lost commentaries on Platonic texts. He is also the author of a text on the astrolabe published in the Catalogus Codicum Astrologorum Graecorum, and lectured on astronomy and geometry. Ammonius taught numerous Neoplatonists, including Damascius, Olympiodorus of Thebes, John Philoponus, Simplicius of Cilicia, and Asclepius of Tralles. Also among his pupils were the physician Gessius of Petra and the ecclesiastical historian Zacharias Rhetor, who became the bishop of Mytilene.