Euthymius of Sardis was an 8th and 9th-century metropolitan bishop who served the see of Sardis. Born in Lycaonia, he became a prominent figure in the Byzantine Empire, particularly known for his staunch defense of icon veneration during the Iconoclast periods. He participated in the Second Council of Nicaea, where he advocated for the restoration of traditional icon worship. Due to his religious convictions, he faced multiple periods of exile and persecution under various emperors, eventually dying as a hieromartyr.