Apollonius of Tyana was a Greek philosopher and holy man from the 1st century CE, active during the Roman Empire. He was a follower of the Pythagorean tradition, known for his ascetic lifestyle, vegetarianism, and extensive travels, which reportedly reached as far as India. His life is known almost exclusively from a biography written about a century after his death by the author Philostratus. This text, commissioned by a Roman empress, portrays Apollonius as a miracle-working sage and critic of tyranny, but modern scholars note that historical facts are difficult to separate from its legendary and stylized narrative.

No writings securely authored by Apollonius survive today. Ancient sources mention lost works, such as a treatise On Sacrifices and a Life of Pythagoras. A collection of letters also exists under his name, but most scholars consider this a later compilation, and its authenticity is disputed.

Apollonius’s significance lies largely in how later generations used his story. According to modern scholars, Philostratus crafted his biography to present Apollonius as an ideal pagan sage and "divine man." In the religious debates of the 3rd and 4th centuries, pagan thinkers cited his life and miracles as a philosophical rival to Jesus Christ. Christian authors, in turn, attacked his reputation. This polemical exchange established Apollonius as a major symbolic figure in the contest between pagan tradition and early Christianity.