a notable Byzantine general and leading aristocrat during the mid-9th century.
Petronas was a brother of Empress Theodora and hence brother-in-law of Emperor Theophilos, under whom he advanced to the rank of patrikios and the post of droungarios of the Vigla regiment. After Theophilos' death, he played a role in the ending of Iconoclasm, but was sidelined along with his brother Bardas during the minority of his nephew, Michael III, when power was held by the regent Theoktistos. In 855, Petronas and Bardas encouraged Michael III to seize control of the government: Theoktistos was murdered, Theodora banished to a monastery, Bardas became Michael's chief minister, and Petronas was tasked with the war against the Arabs. In 863, he scored a crushing victory at the Battle of Lalakaon, a feat which marked the gradual beginning of a Byzantine counter-offensive in the East. Promoted to magistros and domestikos ton scholon, he died in 865