Fomorians

The Fomorians (or Fomor) are a race of superhumanly powerful humanoids who were worshiped by the ancient Celts from about 2000 BC to 350 BC. Two accounts exist on the origins of the Fomorians:
  According to ancient myths, the warrior king Conand coupled with the primordial Earth Mother Gaea / Domnu and produced the first generation of Fomorians, in the subterranean Dark Realm within Otherworld.[2] The Fomorians are the children and descendants of the the Celtic God Nuadhu and the Earth goddess Gaea in her aspect as Danu, the Celtic mother-earth.[11][citation needed][verification needed]
  The exact status of the Fomorians is unknown, but they've been stated to be related to the Tuatha de Danaan,[2] to be a branch of them, or to have an unclear status between demons and evil gods.[10] Bres himself considered them "demonic".[5]