
Fairies are the Little People, said by some to be the dispossessed early tribes of the British Isles. They faded away into uninhabited places, growing smaller and smaller with time as they were forgotten and passed into legend. Oral history informs us that the Tuatha de Danann, People of the Goddess Dana, ruled Ireland before the Milesian invasion. They are said to have been driven underground, where they became the Daoine Sidhe fairies.
Other theories hold that fairies are supernatural beings, fallen angels trapped on earth, spirits of the heathen dead, elementals, nature spirits, visitors from an alternate or parallel universe, or old god/esses who have been so neglected that they have lost their powers and devolved into fairies.