Ecgberht, also spelled Egbert, Ecgbert, Ecgbriht, Ecgbeorht, and Ecbert, was King of Wessex from 802 until his death in 839. His father was King Ealhmund of Kent. In the 780s, Ecgberht was forced into exile to Charlemagne's court in the Frankish Empire by the kings Offa of Mercia and Beorhtric of Wessex, but on Beorhtric's death in 802, Ecgberht returned and took the throne.

Bretwalda is an Old English word. The first record comes from the late 9th-century Anglo-Saxon Chronicle. It is given to some of the rulers of Anglo-Saxon kingdoms from the 5th century onwards who had achieved overlordship of some or all of the other Anglo-Saxon kingdoms. It is unclear whether the word dates back to the 5th century and was used by the kings themselves or whether it is a later, 9th-century, invention. The term bretwalda also appears in a 10th-century charter of Æthelstan. The literal meaning of the word is disputed and may translate to either 'wide-ruler' or 'Britain-ruler'.