Krum

Krum took power sometime between 796 and 803, inheriting a realm and turning it into an empire. Under his rule Bulgarian territory spread from the middle Danube to the Dnieper, from Odrin to the Tatra Mountains — twice the size it had been. He brought law and order to a young state and laid down the first rudiments of organization, the bones of governance. He died on 13 April 814, leaving behind borders that would hold and a name that stuck: the Fearsome.