Cernunnos in Celtic mythology is the deified spirit of horned male animals, especially of stags, a nature god associated with produce and fertility. As a "Horned God", Cernunnos was one of a number of similar deities found in many ancient cultures.
Cernunnos is known, from archaeological sources such as inscriptions and depictions, to have been worshipped in Gaul, Northern Italy (Gallia Cisalpina) and the southern coast of Britain. The earliest known probable depiction of Cernunnos was found at Val Camonica in Italy, dating from the 4th century BC, while the best known depiction is on the famous Gundestrup cauldron of pre-Germanic Denmark, dating from the 1st century BC.
In Gallo-Roman religion, his name is known from the "Pillar of the Boatmen" (Pilier des nautes), a monument now displayed in the Musée Nationale du Moyen Age in Paris. It was constructed by Gaulish sailors in the early first century CE, from the inscription (CIL XIII number 03026) probably in the year 14, on the accession of the emperor Tiberius Claudius Nero. It was found in 1710 in the foundations of the cathedral of Notre-Dame de Paris on the site of Lutetia, the civitas capital of the Celtic Parisii tribe. It depicts Cernunnos and other Celtic deities alongside Roman divinities such as Jupiter, Vulcan, Castor, and Pollux.
The Pilier des nautes provides the earliest written record of the deity's name. Additional evidence is given by two identical inscriptions on metal plaques from Seinsel-Rëlent in Luxembourg, in the territory of the Celtic Treveri tribe. These inscriptions (AE 1987, 0772) read Deo Ceruninco, "to the God Cerunincos". Lastly, a Gaulish inscription (RIG 1, number G-224) written in Greek letters from Montagnac (Hérault, Languedoc-Roussilion, France) reads αλλετ[ει]υος καρνονου αλ[ι]σο[ντ]εας thus giving the name "Carnonos".
While the exact relationships cannot be proven, Cernunnos-like deities exist in non-Celtic cultures: Pan of the Greeks, the Minotaur of the Minoans, and Pashupati, the Hindu Lord of the Animals, are all, or were, horned males associated with nature, animals, and the primordial wild. It is possible that all three entities have a common ancestral origin (a "monomyth"), although what this original image was and its parent culture has not yet been discovered. Nevertheless, the consistency in both representation and role is notable.
Of note is "The Sorcerer," a Paleolithic cave painting representing a therianthropic man with horns. As it predates all known representations of Cernunnos, and the Indo-European cultures associated with him, by several thousand years, it cannot be called with certainty a progenitor image. It does, however, suggest that the idea of a Horned Man held ceremonial, magical, or religious significance as early as the Old Stone Age.
On the Parisii inscription [_]ernunnos, the first letter of the name has been scraped off at some point, but can safely be restituted to "Cernunnos" because of the depiction of an antlered god below the name and the fact that in Gaulish, carnon or cernon means "antler" or "horn" (Delmarre, 1987 pp. 106-107). Similarly cern means "horn" or "bumb, boss" in Old Irish and is etymologically related to similar words carn in Welsh and Breton. These derive from a proto-Indo-European root *krno- which also gave the Latin cornu and Germanic *hurnaz (from which English "horn") (Nussbaum 1986) (Porkorny 1959 pp.574-576). The same Gaulish root is found in the names of tribes such as the Carnutes, Carni, and Carnonacae and in the name of the Gaulish war trumpet, the carnyx. Therefore, the Proto-Celtic form of this theonym can be reconstructed as either *Cerno-on-os or *Carno-on-os, both meaning "horned masculine deity". The -on- is frequently, but not exclusively, found in theonyms (examples: Map-on-os,Ep-on-a, Matr-on-ae, Sir-on-a). Following accepted Celtic sound laws, the Romano-British form of this Proto-Celtic theonym is likely to have been *Cernonos or *Carnonos, both directly comparable to the Gaulish form Cernunnos.
The depictions of Cernunnos are strikingly consistent throughout the Celtic world. His most distinctive attribute are his stag's horns, and he is usually portrayed as a mature man with long hair and a beard. He wears a torc, an ornate neck-ring used by the Celts to denote nobility. He often carries other torcs in his hands or hanging from his horns, as well as a purse filled with coins. He is usually portrayed seated and cross-legged, in a position which some have interpreted as meditative or shamanic, although it may only reflect the fact that the Celts squatted on the ground when hunting.
Cernunnos is nearly always portrayed with animals, in particular the stag. He is also frequently associated with a unique beast that seems to belong primarily to him: a serpent with the horns of a ram. This creature may have been a deity in its own right. He is associated with other beasts less frequently, including bulls (at Reims), dogs and rats. Because of his frequent association with creatures, scholars often describe Cernunnos as the "Lord of the Animals" or the "Lord of Wild Things". Because of his association with stags (a particularly hunted beast) he is also described as the "Lord of the Hunt". Interestingly, the Pilier des nautes links him with sailors and with commerce, suggesting that he was also associated with material wealth as does the coin pouch from the Cernunnos of Reims (Marne, Champagne, France) - in antiquity, Durocortorum, the civitas capital of the Remi tribe - and the stag vomiting coins from Niedercorn-Turbelslach (Luxembourg) in the lands of the Treveri.
Traces of the god survived well into Christian times. The literary traditions of both Wales (he is clearly mentioned in "The Mabinogion" in the tale of the Lady of the Fountain) and Ireland contain allusions to him, while in Brittany the legendary saint Korneli (or Cornély) at Carnac has attributes of Cernunnos. It has also been suggested that the English myth of Herne the Hunter is an allusion to Cernunnos, though this seems doubtful as Herne is thought to be a survival of Saxon, rather than Celtic, beliefs and is first mentioned in 1597 in William Shakespeare's play The Merry Wives of Windsor, Act 4, Scene 4. It is, however, possible that Herne is a much-diluted incarnation of Cernunnos that was absorbed into the collective Saxon pyche.
The Giant of Cerne Abbas in Dorset, England is reputed to be a representation of Cernunnos. This is uncertain, as the image has also been attributed to Hercules and the Dagda. Most obviously, the giant lacks horns.
In Wicca, imagery derived from historical Celtic culture is sometimes used, including a depiction of Cernunnos, often referred to as The Horned God. This version of Cernunnos is based little on historical findings and more on phallic symbolism, merged from elements of Pan. The adherents generally follow a life-fertility-death cycle for Cernunnos, though his death is now usually set at Samhain, the Gaelic New Year Festival usually taking place on October 31. It should be noted, however, that Wicca is in no way an exact reconstruction of historical Celtic religion and culture, despite claims by some Wiccans. 
- Corpus Inscriptionum Latinarum (CIL) volume 13, number 03026
- Delmarre, Xavier (2003) Dictionnarie de la langue gauloise (2nd ed.) Paris: Editions Errance. ISBN 2-87772-237-6
- Lejeune, Michel (1995) Receuil des Inscriptions Gauloise (RIG) volume 1, Textes gallo-grecs. Paris: Editions du CNRS
- Nussbaum, Alan J. (1986) Head and Horn in Indo-European, Berlin, New York: Walter de Gruyter. ISBN 3110104490
- Porkorny, Julius (1959) Indogermanisches etymologisches Wörterbuch Berlin: Franke Verlag