Teutates, important Celtic deity, one of three mentioned by the Roman poet Lucan in the 1st century ad, the other two being Esus (“Lord”) and Taranis (“Thunderer”). According to later commentators, victims sacrificed to Teutates were killed by being plunged headfirst into a vat filled with an unspecified liquid, which may have been ale, a favourite drink of the Celts. Teutates was identified with both the Roman Mercury (Greek Hermes) and Mars (Greek Ares). He is also known from dedications in Britain, where his name was written Toutates. The Irish Tuathal Techtmar, one of the legendary conquerors of Ireland, has a name that comes from an earlier form, Teuto-valos (“Ruler of the People”); he may have been an eponymous deity of the district that he is reputed to have conquered, but he was probably just another manifestation of the great god Teutates.