The Anglo-Saxon settlement of Britain is the migration of several Germanic peoples from the western coasts of Europe and their settlement in Great Britain in the 5th century.

There is no precise date known, save that it began in the early fifth century after the final departure of Roman troops in 410, and continued for some time thereafter.

Their arrival is called the Adventus Saxonum in Latin texts, a characterization first used by Gildas c. 540.

The Adventus Saxonum is the starting point in the history of England, and is traditionally characterized as an invasion rather than a settlement, with differing dates and circumstances suggested as the best conjecture.

Whichever may be best, a measure of the early success of the Anglo-Saxons came in 441, when the Gallic Chronicle of 452 recorded that Britain fell under Saxon domination after suffering many disasters, likely meaning that all contact with the British coast had been cut off by that date.There is ongoing debate, scholarly and otherwise, as to how and why the Anglo-Saxon settlements were successful and as to the full nature of the relationships between the Anglo-Saxons and Romano-Britons, including to what extent the incomers displaced or supplanted the existing inhabitants.

The mostly non-Romanized Britons living in the west and north of Britain were largely unaffected by the Anglo-Saxon settlement.