Basil II

Crowned alongside his brother in 963 before their father died, Basil II and Constantine VIII were too young to hold power; two generals ruled in their place until 976, and even then Basil's great-uncle kept control until 985. The first years as senior emperor meant crushing civil wars against two generals from the Anatolian aristocracy - Bardas Skleros, then Bardas Phokas - which ended only in 989 after Phokas died and Skleros submitted. From there Basil stabilized the eastern frontier, fought the Fatimid Caliphate to a truce in 1000, took part of Crimea from the Khazar Khaganate, campaigned against Georgia, and spent years grinding down the First Bulgarian Empire until it was fully subjugated. He broke the grip of the great landowning families, filled the treasury, and made one cold diplomatic deal that outlasted him: his sister Anna to Vladimir I of Kiev in exchange for soldiers, forming the Varangian Guard and setting the Kievan Rus' on a path to Byzantine Christianity. When he died in 1025 after forty-nine years on the throne, the empire he left was vast and rich - his heirs just couldn't hold it.