King of
Wessex 802-839, and the first person who could be styled King of
England, though he did not control all of the present-day country, but became ruler or
bretwalda (overlord) of all the English kingdoms. He was the founder of a united England, because the dynasty he created continued to expand Wessex, defeating the Danes, gradually absorbing the other kingdoms.
The son of Ealhmund, a Wessex prince who was briefly co-king of Kent, he claimed the throne of Wessex on the death of Cynewulf in 786, but it was taken by Beorhtric, and Egbert went into exile in Charlemagne's court. There had not been a stable dynasty in Wessex for many years, and the last few kings had been distant kinsmen.
He succeeded Beorhtric in 802. He defeated the Cornish, then turned towards Mercia, which at this time controlled most of the minor kingdoms. At the battle of Ellandún in 821 (probably near Winchester) he defeated King Coenwulf of Mercia, became king of Kent in 825, and in 829 he accepted the fealty of Northumbria, the last and most distant of the English kingdoms.
Defeated by Vikings in Dorsetshire in 835, he returned to defeat them and their Cornish allies on the Tamar in 837. He died in 839 and was succeeded by his elder son Æthelwulf in Wessex and Æthelstan as under-king of Kent.
He and his wife Eadburgh (or Redburg) also had a daughter Editha, the abbess of Pellesworth. The name Egbert is modernized; the actual West Saxon was Ecgberht 'bright edge'.
Further reading on these confusing times, are rather useful timeline: http://www.britannia.com/history/saxontime3.html