Egbert (also spelled Ecgberht, Ecgbert or Ecgbriht; 769 or 771 – 839) is King of Wessex from 802 until his death in 839.

His father is Ealhmund of Kent.

In the 780s, Egbert is forced into exile by Offa of Mercia and Beorhtric of Wessex, but on Beorhtric's death in 802 Egbert returns and takes the throne.

Little is known of the first 20 years of Egbert's reign, but it is thought that he was able to maintain the independence of Wessex against the kingdom of Mercia, which at that time dominated the other southern English kingdoms.

In 825, Egbert defeats Beornwulf of Mercia, ended Mercia's supremacy at the Battle of Ellandun, and proceeds to take control of the Mercian dependencies in southeastern England.

In 829, Egbert defeats Wiglaf of Mercia and drives him out of his kingdom, temporarily ruling Mercia directly.

Later this year, Egbert receives the submission of the Northumbrian king at Dore.

The Anglo-Saxon Chronicle subsequently describes Egbert as a bretwalda, or "Ruler of Britain".

Egbert is unable to maintain this dominant position, and within a year, Wiglaf regains the throne of Mercia.

However, Wessex does retain control of Kent, Sussex, and Surrey; these territories are given to Egbert's son Æthelwulf to rule as a subking under Egbert.

When Egbert dies in 839, Æthelwulf succeeds him; the southeastern kingdoms are finally absorbed into the kingdom of Wessex after Æthelwulf's death in 858.