Syrianus was a Neoplatonic philosopher who lived and taught in Athens during the 5th century CE. He became the head, or scholarch, of the Platonic school there, following Plutarch of Athens. His most famous student was Proclus, who would later succeed him. Syrianus led the school during a time when the Roman Empire was predominantly Christian, and his academy was a center for preserving and teaching traditional pagan Greek philosophy.

His major surviving work is a commentary on parts of Aristotle's Metaphysics. In it, he defends Plato's philosophy, especially the theory of Forms, from Aristotle's criticisms. According to modern scholars, this work is a key source for understanding how late Neoplatonists responded to Aristotle's ideas. Syrianus also wrote many other works that are now lost, including commentaries on Homer, Orphic poems, and Plato's Phaedrus, as well as treatises on theology and rhetoric. The authenticity of some works on rhetorical topics is disputed.

Syrianus is considered a pivotal figure in the history of the Athenian school. His significance lies in his role as a teacher and systematizer who shaped its curriculum. He taught Proclus, who became the most influential systematizer of late Neoplatonism. Syrianus's approach, which placed Plato as the supreme philosophical authority while using Aristotle as an introduction, defined the school's teaching method. His ideas on finding philosophical truth in ancient poetry through allegory also deeply influenced his student Proclus.