Belenus
Belenus (Belinus or Bel) Was worshipped in North Italy, Gaul and Britian. Fires are lit in his honour at Beltane May's eve, 30th April, and cattle were driven between them as a purfying rite.
Bel is affiliated with Apollo, the ancient Greek/Roman fire god.
The Druid worshippers of Bel were an intellectual order who passed their knowledge and teachings on through word of mouth. Most were slaughtered with their families by the invading Romans, who then set about the task of associating different names to the native Celtic gods, and much of the knowledge was lost.
Adapted from 'A guide to the Gods' by Richard Carlyon
