Alexander of Aphrodisias (Ἀλέξανδρος ὁ Ἀφροδισιεύς; AD) was a Peripatetic philosopher and the most celebrated of the Ancient Greek commentators on the writings of Aristotle. He was a native of Aphrodisias in Caria and lived and taught in Athens at the beginning of the 3rd century, where he held a position as head of the Peripatetic school. He wrote many commentaries on the works of Aristotle, extant are those on the Prior Analytics, Topics, Meteorology, Sense and Sensibilia, and Metaphysics. Several original treatises also survive, and include a work On Fate, in which he argues against the Stoic doctrine of necessity; and one On the Soul. His commentaries on Aristotle were considered so useful that he was styled, by way of pre-eminence, "the commentator" (ὁ ἐξηγητής).
Alexander was a native of Aphrodisias in Caria (present-day Turkey) and came to Athens towards the end of the 2nd century. He was a student of the two Stoic, or possibly Peripatetic, philosophers Sosigenes and Herminus, and perhaps of Aristotle of Mytilene. At Athens he became head of the Peripatetic school and lectured on Peripatetic philosophy. Alexander's dedication of On Fate to Septimius Severus and Caracalla, in gratitude for his position at Athens, indicates a date between 198 and 209. A recently published inscription from Aphrodisias confirms that he was head of one of the Schools at Athens and gives his full name as Titus Aurelius Alexander. His full nomenclature shows that his grandfather or other ancestor was probably given Roman citizenship by the emperor Antoninus Pius, while proconsul of Asia. The inscription honours his father, also called Alexander and also a philosopher. This fact makes it plausible that some of the suspect works that form part of Alexander's corpus should be ascribed to his father.
Alexander composed several commentaries on the works of Aristotle, in which he sought to escape a syncretistic tendency and to recover the pure doctrines of Aristotle. His extant commentaries are on Prior Analytics (Book 1), Topics, Meteorology, Sense and Sensibilia, and Metaphysics (Books 1–5).