Amadan Dubh, also known as the Dark Fool or Fairy Fool, is a trickster fairy found in Irish folklore, and is the "bringer of madness and Oblivion."
It is also said that Amadan Dubh "haunts the hills after sunset playing reed pipes to work his magic." Other fairies that resemble Amadan Dubh are the Amadan, Amadan Mor, Amadan-Na-Briona, Amadan-Na-Bruidne, all also from Ireland.
Source
The Illustrated Encyclopedia of Fairies, Anna Franklin and Illustrated by Paul Mason and Helen Field.