Balor The Irish Cyclops

Balor was the Irish Cyclops, this one-eyed god of death was the most formidable of the Fomorii, the violent and monstrous sea gods who ruled Ireland before the arrival of the Tuatha De Dannan. So dreadful was his one eye that he destroyed whoever he looked upon and his eyelid had to be levered up by four servants. It was prophesied that he would be slain by his own grandson. To avoid this fate he locked his only daughter Ethlinn in a crystal tower on Tory Island, off the north-west coast of Ireland. Even so, later Balor was killed in battle with a sling-shot by the sun god Lugh, Ethlinn's son and the champion of the Tuatha De Danann.

Lugh's father was Cian, a lesser member of the Tuatha De Danann With the assistance of a female druid, Cian had entered the crystal tower and slept with Ethlinn. When Balor learned that his daughter had given birth to three sons, he ordered that they be drowned in a whirlpool near Tory Island. Balor's servants duly rolled them up in a sheet, but on the way to the whirlpool one of the boys fell out unnoticed Either the druid then handed the fortunate baby to the smith god Goibhniu, or alternatively Manannan Mac Lir, the god of the sea, decided to foster him. ln either event, Lugh was saved and set on the road to his destiny as the slayer of Balor.

Lugh eventually becomes king of the Tuatha De Danann. He leads the Tuath De in the second Battle of Mag Tuired against the Fomorians, who are led by Balor. Ogma, one of the member of Tuatha De Dannan disarms Balor during this battle, but Balor kills Nuada (the first king of the Tuatha De Danann) with his eye. Finally, Lugh kills Balor by casting a sling, or a spear crafted by Gobniu, through his eye. Balor's eye destroys the Fomorian army and then Lugh beheads Balor.

One legend tells that, when Balor was slain by Lugh, Balor's eye was still open when he fell face first into the ground. Thus his deadly eye beam burned a hole into the earth. Long after, the hole filled with water and became a lake which is now known as Loch na Súil, or "Lake of the Eye", in County Sligo.

Sources:

Encyclopedia of Mythology written by Arthur Cotterell

https://en.wikipedia.org/wiki/Balor

Pic Source:

Encyclopedia of Mythology written by Arthur Cotterell page 102