Egbert (also Ecgberht or Ecgbert) (c. 770– July 839) was King of Wessex from 802 until his death. Under Egbert, Wessex rose to become the most powerful of the Anglo-Saxon kingdoms, overthrowing the supremacy of Mercia.
A somewhat difficult question has arisen as to the parentage of Egbert. Under the year 825, the Anglo-Saxon Chronicle states that in his eastern conquests Egbert recovered what had been the rightful property of his kin. The father of Egbert was called Ealhmund, and we find an Ealhmund, king in Kent, mentioned in a charter dated 784, who is identified with Egbert's father in a late addition to the Chronicle under the date 784. It is possible, however, that the Chronicle in 825 refers to some claim through Ine of Wessex from whose brother Ingeld Egbert was descended.
After the murder of King Cynewulf in 786, Egbert may have contested the succession, but the throne went to Beorhtric, an ally of Offa of Mercia. Starting probably in 789, Egbert went into exile after being expelled by Offa and Beorhtric. He spent this exile with the Franks on the continent, and although it is said to have lasted three years, some historians have suggested that this period may have actually lasted thirteen years (789–802), as this would account for Egbert's whereabouts during the whole period preceding Beorhtric's death.
Beorhtric ruled subject to the Mercian kings (Offa and, from 796, Coenwulf), and Egbert probably sought greater independence for Wessex. He was acknowledged as king by the West Saxons following Beorhtric's death in 802, but on the same day as his accession to the throne, Ælthelmund, earl of the Hwicce, led a raid into Wessex. Ælthelmund was defeated and killed by Weoxtan, earl of Wiltshire, who also lost his life in the battle.
In 815 Egbert ravaged the whole of the territories of the West Welsh, which probably at this time did not include much more than Cornwall; it is probably from his reign that Cornwall can be considered subject to Wessex. The next important occurrence in the reign was the defeat of Beornwulf of Mercia at a place called Ellandun in 825. After this victory, Kent, Surrey, Sussex and Essex submitted to Wessex; while the East Anglians, who rose against Mercian rule and slew Beornwulf shortly afterwards, acknowledged Egbert as overlord. In 829 the king conquered Mercia, and Northumbria accepted him as overlord after refusing to fight his forces at Dore (now a suburb of Sheffield). In 830 he led a successful expedition against the Welsh, and it was in the same year that Mercia regained its independence under Wiglaf, although it is uncertain whether this was achieved through a rebellion or was the result of a grant by Egbert to Wiglaf. In 836 Egbert was defeated by the Danes, but in 838 he won a battle against them and their allies the West Welsh at Hingston Down in Cornwall.
Egbert married Redburga, a Frankish princess (possibly a sister-in-law of the emperor Charlemagne), and had two sons and a daughter. Egbert died in about 839, and was buried at Winchester. He was succeeded by his son, King Ethelwulf of Wessex.