Egbert, also spelled ECGBERHT, or ECGBRYHT (d. 839), king of the West Saxons from 802 to 839, who formed around Wessex a kingdom so powerful that it eventually achieved the political unification of England (mid-10th century). The son of Ealhmund, king in Kent in 784 and 786, Egbert was a member of a family that had formerly held the West Saxon kingship.

In 789 Egbert was driven into exile on the European continent by the West Saxon king Beorhtric and his ally, the powerful Mercian king Offa (d. 796). Nevertheless, Egbert succeeded to Beorhtric's throne in 802. He immediately removed Wessex from the Mercian confederation and consolidated his power as an independent ruler.
In 825 he decisively defeated Beornwulf, king of Mercia, at the Battle of Ellendune (now Wroughton, Wiltshire). The victory was a turning point in English history because it destroyed Mercian ascendancy and left Wessex the strongest of the English kingdoms. By virtue of long-dormant hereditary claims, Egbert was accepted as king in Kent, Sussex, Surrey, and Essex.

In 829 he conquered Mercia itself, but he lost it in the following year to the Mercian king Wiglaf. A year before his death Egbert won a stunning victory over Danish and Cornish Briton invaders at Hingston Down (now in Cornwall).