The Earl of Northumbria was a title in the medieval English nobility, associated with the region of Northumbria in northern England. This title was held by various noble families, particularly during the Anglo-Saxon period. The earldom played a significant role in the governance and military leadership of the area, especially during conflicts with the Scots and Vikings. The title has historical significance, with notable earls such as Oswald and Siward. The earldom eventually became part of the larger title of the Duke of Northumberland after the Norman Conquest, reflecting the changes in the English aristocracy over time.