In Gallo-Roman religion, Epona [e po nə] was a protector of horses, donkeys, and mules. She was particularly a goddess of fertility, as shown by her attributes of a patera, cornucopia, and the presence of foals in some sculptures (Reinach, 1895). And H. Hubert suggested that the goddess and her horses were leaders of the soul in the after-life ride, with parallels in Rhiannon of the Mabinogion. Unusually for a Celtic deity, most of whom were associated with specific localities, the worship of Epona, "the sole Celtic divinity ultimately worshiped in Rome itself", was widespread in the Roman Empire between the first and third centuries CE.
Her feast day in the Roman calendar was December 18 as shown by a rustic calendar from Guidizzolo, Italy, although this may have been only a local celebration. She was incoporated into Imperial cult by being invoked on behalf of the Emperor, as Epona Augusta or Epona Regina.
The supposed autonomy of Celtic civilisation in Gaul suffered a further setback with Fernand Benoit's study of the funereal symbolism of the horseman with the serpent-tailed ("anguiforme") daemon, which he established as a theme of victory over death, and Epona; both he found to be late manifestations of Mediterranean-influenced symbolism, which had reached Gaul through contacts with Etruria and Magna Graecia. Benoit compared the rider with most of the riders imaged around the Mediterranean shores.
Perceptions of native Celtic goddesses had changed under Roman hegemony: only the names remained the same. As Gaul was Romanized under the early Empire, Epona’s sovereign role evolved into a protector of cavalry. The cult of Epona was spread over much of the Roman Empire by the auxiliary cavalry, alae, especially the Imperial Horse Guard or equites singulares augustii recruited from Gaul, Lower Germany, and Pannonia. A series of their dedications to Epona and other Celtic, Roman and German deities was found in Rome, at the Lateran. As Epane she is attested in Cantabria, northern Spain, on Mount Bernorio, Palencia.
A bizarre euhemeristic account of the birth of Epona that does not reflect Celtic beliefs can be found in Plutarch's life of Solon: Giambattista Della Porta's edition of Magia naturalis (1589), a potpourri of the sensible and questionable, remarks, in the context of unseemly man-beast coupling, Plutarch's Life of Solon, in which he "reports out of Agesilaus, his third book of Italian matters, that Fulvius Stella loathing the company of a woman, coupled himself with a mare, of whom he begot a very beautiful maiden-child, and she was called by a fit name, Epona..."
Sculptures of Epona fall into five types, as distinguished by Benoit: riding, standing or seated before a horse, standing or seated between two horses, a tamer of horses in the manner of potnia theron and the symbolic mare and foal. In the Equestrian type, common in Gaul, she is depicted sitting side-saddle on a horse or (rarely) lying on one; in the Imperial type (more common outside Gaul) she sits on a throne flanked by two or more horses or foals. In distant Dacia, she is represented on a stela (now at the Szépmüvézeti Museum, Budapest) in the format of Cybele, seated frontally on a throne with her hands on the necks of her paired animals: her horses are substitutions for Cybele's lions.
Epona is mentioned in The Golden Ass by Apuleius, where an aedicular niche with her image on a pillar in a stable has been garlanded with freshly-picked roses. In his Satires, the Roman poet Juvenal also links the worship and iconography of Epona to the area of a stable. Small images of Epona have been found in Roman sites of stables and barns over a wide territory.
The probable date of ca. 1400 BCE ascribed to the giant chalk horse carved into the hillside turf at Uffington, in southern England, is too early to be directly associated with Epona a millennium and more later, but clearly represents a Bronze Age totem of some kind. The English traditional hobby-horse riders parading on May Day at Padstow, Cornwall and Minehead, Somerset, which survived to the mid-twentieth century, even though Morris dances had been forgotten, may have deep roots in the veneration of Epona, as may the English aversion to eating horsemeat. At Padstow formerly, at the end of the festivities the hobby-horse was ritually submerged in the sea.