ruler of a large area of southeastern Britain from roughly AD 10 to 42. He is the Cymbeline in William Shakespeare's play of that name, but the play's fanciful plot bears no relation to the events in Cunobelinus's career.

Cunobelinus succeeded his father, Tasciovanus, as chief of the Catuvellauni, a tribe centred north of what is now London. Tasciovanus's capital was Verlamio, above the later Roman site of Verulamium (modern St. Albans). Either shortly before or shortly after his accession, Cunobelinus conquered the territory of the Trinovantes, in modern Essex. He made Camulodunum (modern Colchester) his capital and the seat of his mint. The many surviving coins from the mint are stamped with Latin slogans and figures from mythology. His power and influence were so extensively felt in Britain that the Roman biographer Suetonius referred to him as Britannorum rex (“King of the Britons”) in his life of the emperor Caligula. About AD 40 Cunobelinus banished his son Adminius, who thereupon fled to Rome and persuaded Caligula to make preparations to invade Britain. The expedition was assembled, but it never left the continent. After Cunobelinus's death, his two other sons, Caratacus and Togodumnus, displayed the hostility toward Rome that gave the emperor Claudius an excuse to impose Roman rule on the island.