Aethelwald (d. after 655) was a King of Deira (651 - c. 655). He was the son of Oswald of Northumbria.

After Oswine of Deira was killed by King Oswiu of Northumbria in 651, Aethelwald became king. In 652 or 653, he allied himself with Oswiu's enemy, Penda of Mercia, and according to Bede, he acted as Penda's guide during the latter's invasion of Northumbria in 655. However, when the armies of Oswiu and Penda met on November 15 at the Battle of Winwaed, Aethelwald withdrew his forces. Penda was defeated, perhaps in large part because of this desertion, and afterward Aethelwald seems to have lost Deira to Alchfrith , who was installed there by the victorious Oswiu. Aethelwald's fate is unknown.

Although he allied himself with the pagan Penda, Aethelwald was nevertheless a pious Christian and was remembered for his generosity towards St Chad, to whom he granted land for a monastery.