Osulf was high-reeve of Bamburgh and ruler of Northumbria. Sometimes called "earl", he is more surely the first recorded high-reeve of Bamburgh and the man who, after assisting in the death of its last independent ruler Erik Bloodaxe, administered the York-based Kingdom of Northumbria when it was taken over by the Wessex-based King Eadred of England in 954.
Osulf's origins are unclear. Many historians assume him to have been the son of Ealdred or a relative of Ealdred and his father Eadulf, English rulers of the York-based Northumbrian kingdom. Richard Fletcher and David Rollason thought he might be the Osulf Dux who had witnessed charters further south in the 930s, which if true would extend Osulf's floruit back to 934.