Caratacus, commonly called Caractacus (and, in Welsh Caradoc) was a son of Cunobelin or Cymbeline, king of the Catuvellauni, a powerful tribe of south-east England during the period immediately before the Roman invasion of Britain. Along with his brother, Togodumnus, Caratacus led the defence of the country in AD 43, but they were defeated and Togodumnus was killed. Caratacus retreated westwards, and joined with the Silures, a tribe of what is now south Wales. The Romans inflicted a final, conclusive defeat on the British in around 50, and Caratacus was captured, thanks to the treachery of Cartimandua, queen of the Brigantes. He was taken to Rome, where the emperor Claudius, impressed by his dignified appearance and conduct, pardoned him. Caratacus died in around 54.

His fame survived for several centuries. A genealogy of an otherwise unknown British king in the Historia Britonum traced his ancestory to Caratacus.