Simplicius of Cilicia was a Neoplatonic philosopher of the sixth century CE. He studied in Alexandria and later in Athens, where he belonged to a circle of pagan philosophers. This group came under pressure after the Christian emperor Justinian issued an edict in 529 restricting pagan teaching. Historical accounts relate that Simplicius and several colleagues sought temporary refuge at the court of the Persian king Khosrow I. A subsequent peace treaty guaranteed their safe return to the Eastern Roman Empire, though his exact whereabouts in his later years remain unknown.

He is renowned for his extensive and detailed commentaries on the works of Aristotle. His major surviving works include commentaries on Aristotle's Categories, Physics, On the Heavens, and On the Soul. He also wrote a commentary on the Handbook of the Stoic philosopher Epictetus. These are not simple explanations but comprehensive scholarly treatises.

Modern scholars regard Simplicius as a figure of immense importance, primarily for his role in preserving earlier philosophical thought. His commentaries quote extensively from many earlier Greek thinkers, including Pre-Socratic philosophers and other schools, whose original works are now lost. This makes his writings an indispensable source for reconstructing the history of philosophy and science. His work represents a late Neoplatonic synthesis that sought to harmonize Aristotle with Plato. Through Byzantine, Arabic, and later Renaissance channels, his commentaries were instrumental in transmitting Aristotelian ideas to later intellectual traditions.