Anglo-Saxon king of Northumbria from 633 to 642 who introduced Celtic Christian missionaries to his kingdom and gained ascendancy over most of England.

Oswald's father, King Aethelfrith (d. 616), had ruled the two ancient Northumbrian kingdoms of Bernicia and Deira. Expelled from Northumbria upon the accession of his uncle Edwin in 616, Oswald and his brother Oswiu took refuge in Iona in the Hebrides, where they were converted to Christianity.

Edwin was killed fighting King Cadwallon of Gwynedd (in northern Wales) and Penda of Mercia in 633, but the next year Oswald defeated and killed Cadwallon near Hexham (in present-day Northumberland). At Oswald's invitation, St. Aidan led a group of Irish monks from Iona to found a monastery and missionary bishopric for the kingdom at Lindisfarne. The historian Bede says that he asserted his authority over all the peoples of southern England. The pagan king Penda defeated and killed Oswald at Maserfelth (or Maserfeld, probably near Oswestry, in present-day Shropshire). The dead king was venerated as a martyr of the Northumbrian church, and it was believed that his remains worked miracles.