(Celtic: possibly, Bright One), one of the most ancient and most widely worshipped of the pagan Celtic deities; he was associated with pastoralism. A great fire festival, called Beltane (or Beltine), was held on May 1 and was probably originally connected with his cult. On that day the cattle were purified and protected by fire before being put out to the open pastures for the summer. Despite associations of his name with fire or the sun, Belenus was not a sun god; in fact, there is no Celtic evidence for the worship of the sun as such, even though it was often used in religious imagery.

There are about 31 extant dedications to Belenus, an unusually high number for a religion that specialized in the number and diversity of its divine names and epithets. The cult of Belenus was practiced in northern Italy, Noricum in the eastern Alps, southern Gaul, and probably Britain.