Breton mythology is the mythology or corpus of explanatory and heroic tales originating in Brittany. The Bretons are the descendants of insular Britons who settled in Brittany from at least the third century. While the Britons were already Christianised in this era, the migrant population maintained an ancient Celtic mythos, similar to those of Wales and Cornwall.
Breton mythology has many gods and mythical creatures specifically associated with nature cults. In this tradition of gods and creatures rooted in nature, there exist traces of certain Breton Catholic saints. This mythological background was accepted by Romans who were soon Christianized, resulting in the irrevocable loss of grand epics and the destruction or conversion of pagan landmarks and places.