Today, he is best known under the name Toutatis (pronounced [towˈtaːtis] in Gaulish) through the Gaulish oath/catchphrase "By Toutatis!", invented for the Asterix comics by Goscinny and Uderzo. The spelling Toutatis is authentic and attested by about ten ancient inscriptions. Under the spelling Teutates, the god is also known from a passage in Lucan.
Teutates was one of three Celtic gods 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. Of two later commentators on Lucan's text, one identifies Teutates with Mercury, the other with Mars.
Toutatis was worshipped especially in Gaul and in Roman Britain. Inscriptions to him have been recovered in the United Kingdom, for example that at Cumberland Quarries (RIB 1017), dedicated to Jupiter Optimus Maximus and Mars Toutatis. Two dedications have also been found in Noricum and Rome.
As noted above, among a pair of later scholiasts on Lucan's work, one identifies Teutates with Mercury and Esus with Mars. At times the Gaulish “Mercury" may have the characteristic of a warrior, while the Gaulish “Mars" may act as a god of protection or healing.
Paul-Marie Duval argues that each tribe had its own toutatis; he further considers the Gaulish Mars the product of syncretism with the Celtic toutates, noting the great number of indigenous epithets under which Mars was worshipped.
A large number of Romano-British finger rings inscribed with the name "TOT", thought to refer to Toutatis, have been found in eastern Britain, the vast majority in Lincolnshire, but some in Bedfordshire, Nottinghamshire and Leicestershire. The distribution of these rings closely matches the territory of the Corieltauvi tribe. In 2005 a silver ring inscribed DEO TOTA ("to the god Toutatis") and [VTERE] FELIX ([use this ring] happily") was discovered at Hockliffe, Bedfordshire. This inscription confirmed that the inscription TOT did indeed refer to the god Toutatis.
In 2012 a silver ring inscribed "TOT" was found in the area where the Hallaton Treasure had been discovered twelve years earlier. Adam Daubney, an expert on this type of ring, suggests that Hallaton may have been a site of worship of the god Toutatis.