Boso was the Earl of Oxford under Arthur. In Malory, his role is taken by Bors.
Note
A member of the nobility. The title earl is Anglo-Saxon and is the same as the Scandinavian jarl (‘chieftain’), they ruled their territories in a king’s stead. During the medieval times, in Scandinavia, the title was replaced with hertig, duke, which later on became equivalent with Count on the Continent.