Alexander of Aphrodisias was a Greek philosopher who lived and worked in the late second and early third centuries CE, during the Roman Empire. He was from the city of Aphrodisias in Asia Minor. He moved to Athens, where he held the official, state-funded chair in Peripatetic philosophy, a position dedicated to teaching the tradition of Aristotle. His appointment is dated to between 198 and 209 CE.

He is best known as the most important ancient commentator on the works of Aristotle. For this, he earned the nickname "the commentator." His extensive writings include detailed commentaries on Aristotle's Prior Analytics, Topics, Meteorology, and Metaphysics, among others. He also wrote independent philosophical treatises. Key surviving works include On Fate, a major defense of free will against Stoic determinism, and On the Soul, which explores Aristotle's theory of mind. Some works attributed to him are considered by modern scholars to be spurious.

Alexander of Aphrodisias played a crucial role in the history of philosophy. According to scholars, he revived and systematized Aristotelian thought, actively defending it against rival schools like Stoicism. His interpretations became the standard authority for later Greek, Arabic, and medieval Latin philosophers. His arguments about fate, the soul, and the nature of intellect were foundational and widely debated for centuries after his death.