The Fomorians are a group of supernatural beings from Irish mythology, often portrayed as hostile and monstrous, said to come from under the sea or the earth. In Irish mythology, the Fomorians were said to have arrived in Ireland before the Tuatha Dé Danann, the mythical race of gods who are often portrayed as the main protagonists of Irish mythology. The Fomorians were said to have been the original inhabitants of Ireland, and they were eventually defeated and subjugated by the Tuatha Dé Danann.

Despite their defeat, the Fomorians remained a significant force in Irish mythology, and they are often portrayed as a symbol of chaos and destruction. They are associated with the sea and with storms, and they are sometimes depicted as raiders and pirates. The Fomorians are also sometimes associated with the Otherworld, the mystical realm that exists alongside the mortal world in Irish mythology.