Andronikos III Palaiologos

Andronikos III Palaiologos was proclaimed co-emperor before 1313, the son of Michael IX Palaiologos and Rita of Armenia. In April 1321 he rebelled against his grandfather, Andronikos II, was formally crowned co-emperor in February 1325, and ousted the old man entirely to become sole Byzantine emperor on 24 May 1328. His reign saw the last failed attempts to hold back the Ottoman Turks in Bithynia and a defeat at Rusokastro against the Bulgarians, but he successfully recovered Chios, Lesbos, Phocaea, Thessaly, and Epirus. He died on 15 June 1341, leaving a power vacuum that erupted into civil war between his widow, Anna of Savoy, and his closest friend John VI Kantakouzenos - a disaster that opened the door for the Serbian Empire's rise and the Ottoman Empire's entry into the Balkans.