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Osullf (c. 810–867) was the son of Oswulf of Northumbria, who ruled Northumbria for a brief period in 808. In 848, Osullf led an army of Northumbrians to aid Ecgbert of Wessex against the Mercians, and was rewarded by being appointed the first ealdorman of the whole of Northumbria. He ruled Northumbria until his death in 867.