The Fomorians (Fomhóraigh)

A race often depicted as monstrous or chaotic beings, traditional rivals to the Tuatha Dé Danann.

The Fomorians were a supernatural race of giants and sea-raiders who inhabited Ireland in ancient times, often described as the dark counterparts to the Tuatha Dé Danann. They represented chaos, darkness, and the destructive powers of nature.

While often depicted as monstrous—some with only one eye, one arm, or one leg—others, like Elatha, were described as stunningly beautiful. They were not a "wave" of settlers but were already present, lurking in the seas or on remote islands like Tory Island, harassing each group of new arrivals.

Their most fearsome leader was Balor of the Evil Eye, whose gaze could kill instantly. The Fomorians were finally defeated at the Second Battle of Moytura by the Tuatha Dé Danann, when Lugh (Balor's own grandson) killed Balor with a sling-stone through his eye.