Balor

Balor is the leader of the Fomori and the enemy of Dagda and the entire Celtic pantheon - once a noble deity of great power and beauty Balor would fall into Twilight Corruption alongside his entire pantheon and became a monstrous enforcer of the Watchers, confined to the depths of the oceans Balor and the Fomori continue to be an active threat to both the world of mortals and deities alike.

Although not part of the Fomori the ancient sea-demon known as Nuckelavee was actually a "pet" of Balor prior to its own corruption - Balor has since abandoned it to the ocean.