A Roman gens which seems to have supplied the name Arthur. Evidence of the gens is found in the first-century writings of the Roman historian Cornelius Tacitus and the Roman poet Juvenal (Decimus Iunius Iuvenalis).

The name was known in Roman Britain as early as the second century: an officer named Lucius Artorius Castus led a military excursion into Brittany around 150 a.d.