Illidius was a 4th-century bishop from the Auvergne region of France. Serving the community of Clermont, he played a significant role in establishing the city as a prominent center for religious culture and learning. His historical presence is noted by Gregory of Tours, who recorded his life and deeds. He is remembered for a miraculous healing performed in Trier, where he cured the daughter of the emperor Magnus Maximus, an event that occurred during his travels.