The mythology of the ancient Basques largely did not survive the, albeit late, arrival of Christianity in the Basque Country between the 4th and 12th century AD. Most of what is known about elements of this original belief system is based on the analysis of legends, the study of place names and scant historical references to pagan rituals practised by the Basques.
* Mari or Maddi was a goddess of the Basques. The most prominent mythical being of the Basque traditions, without any doubt, and a beautiful woman. She habitually resides in the interior of the Earth and emerges at the surface in specific epochs via various caves and caverns. She alternates, therefore, moving from one mountain to another before the amazed look of man. Mari is beautiful and dressed in elegance, the quintessential essence of feminine guile. At other times, she adopts the form of different animals, or becomes a ball of fire crossing the horizon.
The quality of her personal affects, such as her household furnishings, is considered the equivalent of solid gold, as prime example of the magnificance corresponding to her station. Haughty and arrogant in the defense of her interests, she allows no mortal to enter her dwelling, so that none of her personal goods are unduly appropriated. Mari has powers that allow her to reduce the stolen gold to coal with the simple contact of day light; and she knows how to tell the coal to turn into gold, the good services.
At times it is risky to approach her, including her cave. She does not put up with the shepherds building their cabins in the environs of Supelegor. One such was pursued by the Lady, transformed into a raven, and although he escaped with his life, he died shortly afterwards as a consequence of the scare. The geography of Mari's influence was at one time more extensive than it is today. The children of la Burunda called the leftovers of the meal with bread that the men brought when they returned home «bread of Mari of the mountain», basoko Mariren ogia. And, to the south of Urbasa, in Améscoa, this custom continued until very recently: they used to tell the children «Eat the bread of the old woman of the mountain» or also, «bread of the little grandmother of the mountain».
There are also areas where the traditions of this spirit are still very much alive, but where they do not use her name. They call her, simply, the Lady, Damea. Theses stories, however, are usually very similar and refer to the same person. Mari's spouse is Maju or Sugaar and her children are Attarrabi and Mikelats. According to the traditions of Arbizu, she continues to appear from time to time, the Lady of Aizkorri. She moved from the cave at Putterri, in Aralar, to the mountains of Cegama along the slope of the mount. The legends of Mari have, on the other hand, a very significant religious connotation. Repeatedly, the refusal of Christian practices by part of the protagonist is demonstrated; the origin of her marginalized life is even attributed to this rebellion.
Other mythical beings
* Aatxe: or Etsai is a cave-dwelling evil spirit who adopts the form of a young red bull, but being a shapeshifter, sometimes takes the shape of a man.
* Atxular and Mikelatz are said to be sons of Mari, among others.
* Basajaun: the wild man of the woods and his female version: basandere.
* Galtzagorriak are a specific type of iratxoak (imps).
* Gaueko is an evil character of the night.
* Herensuge is the name of a dragon who plays an important role in a few legends.
* Erge is an evil spirit that takes men's lives.
* Ilargi or Ile are the known names of the Moon, also a daughter of Ama Lur, the Mother Earth.
* Iratxoak: imps.
* Jentilak (gentiles): giants, sometimes portrayed throwing rocks at churches. They are believed to be pagan Basques themselves, seen from a partly Christianized viewpoint. A surviving jentil is Olentzero, the Basque equivalent of Santa Claus.
* Lami(n)ak, a type of nymph with bird-feet that dwelt in rivers and springs.
* Mairuak or Intxisuak are the male equivalent of lamiak in the Pyrenean region, where they are said to have built up the cromlechs.
* Odei is a personification of storm clouds.
* Martin Txiki, a popular local Christian character, is a trickster.
* Sorginak are both mythological beings that travel with Mari and real witches.
* Tartalo: the Basque version of the Greco-Roman Cyclops.