The ancient Celts had hundreds of deities, but as with most cultures, they had their demons as well. Some of the Celtic “monsters” were originally gods, but were later demonized as pagan creatures when many of the Celts became Christians. But the Celtic culture has always feared an array of evil forces.
Dragon Wood Carving
The Book of Kells, created by Celtic monks, is on of the most intricate pieces of art I've ever wished to see. BTW it "is an illuminated manuscript Gospel book in Latin," as quoted from wiki.