The Catuvellauni (Common Brittonic: *Catu-wellaunī, "war-chiefs") were a Celtic tribe or state of southeastern Britain before the Roman conquest, attested by inscriptions into the 4th century.
The fortunes of the Catuvellauni and their kings before the conquest can be traced through ancient coins and scattered references in classical histories. They are mentioned by Cassius Dio, who implies that they led the resistance against the conquest in AD 43. They appear as one of the civitates of Roman Britain in Ptolemy's Geography in the 2nd century, occupying the town of Verlamion (modern St Albans) and the surrounding areas of Hertfordshire, Bedfordshire and southern Cambridgeshire.
