Donn is the ancient Celtic god of the Dead who rules the rocky islands to the south west on the Atlantic coast. Donn is also known in Co. Fermanagh as the ancestor of the Maguires, whom he helped in their battles. Sometimes he is seen riding on a white horse on stormy nights, when people would exclaim: "Donn is galloping in the clouds tonight". Donn now more closely resembles a medieval Irish landlord than a god. He rules quite strictly but will aid his people when needed. He is also believed to fight against rival hosts in other counties, the winner carrying off the best potato crop for that year.

It will be noted that the fairy queens and kings are in fact the old pagan gods and goddesses 'in disguise' who have long been revered by the Irish. It has been said that the Celtic gods of Ireland had long been wiped out, buried under the sway of Catholicism. Yet anyone who has been to Ireland, or listened to her many folk tales can see for themselves that this is very far from the reality.

The old gods live on in folk tales as the giants of the hill; the Gobhan Saor who built all the bridges of Ireland; the Gille Decair, a clown and trickster; the carl (serf) of the drab coat and many others.

The old deities were once worshipped throughout Ireland, however it is in the west that they are best remembered now, the east having been more Christianised and anglicised, and subject to more invasions. By contrast, the west of Ireland, to which the native Irish were driven ("to hell or Connaught") has held on longer to her ancient heritage.