Æthelberht (Old English: Æðelbrihte, ÆÞelberhte), also called Saint Ethelbert the King (died 20 May 794 at Sutton Walls, Herefordshire), was an eighth-century saint and a king of East Anglia, the Anglo-Saxon kingdom which today includes the English counties of Norfolk and Suffolk. Little is known of his reign, which may have begun in 779, according to later sources, and very few of the coins he issued have been discovered. It is known from the Anglo-Saxon Chronicle that he was killed on the orders of Offa of Mercia in 794.

Æthelberht was locally canonised and became the focus of cults in East Anglia and at Hereford, where the shrine of the saintly king once existed. In the absence of known historical facts, mediaeval chroniclers provided their own details for his ancestry, life as king, and death at the hands of Offa. His feast day is 20 May. There are churches in Norfolk, Suffolk and the west of England dedicated to him, and he is a joint patron of Hereford Cathedral.