Earl of Northumbria or Ealdorman of Northumbria was a title in the late Anglo-Saxon, Anglo-Scandinavian and early Anglo-Norman period in England.
The ealdordom was a successor of the Norse Kingdom of York.
Southern Northumbria, the former Deira, then became the Viking kingdom of York, while the rulers of Bamburgh commanded territory roughly equivalent to the northern kingdom of Bernicia.
In 1006 Uhtred the Bold, ruler of Bamburgh, by command of Æthelred the Unready became ealdorman in the south, temporarily re-uniting much of the area of Northumbria into a single jurisdiction.
After the Norman Conquest the region was divided into multiple smaller baronies, one of which was the earldom of Northumberland, with others like the earldoms of York and numerous autonomous liberties such as the County Palatine of Durham and Liberty of Tynedale.