Heliodorus of Catania (Italian: Eliodoro, pronounced [eljoˈdɔːro]; died Catania, 778) is a semi-legendary personage accused by his contemporaries of being a necromancer practicing witchcraft.

Son of a noble Sicilian family, he was originally a Christian, and was even a candidate to assume the diocese of Catania. In that period the Etnean City came under the jurisdiction of the Eastern Roman Empire governed by then-Emperor Leo III the Isaurian.

Having failed to attain the office of bishop, conferred instead on an archdeacon from Ravenna named Leo, he apostatized from the faith and began to practice magic and sorcery.

Besides the accusation of necromancy, Heliodorus was pointed to as an idolmaker and "a disciple of the Jews". He remained a vocal opponent of Saint Leo Thaumaturgus, who led the church of Catania as bishop from A.D. 765 to 785.