In Irish mythology, Balor or Balar was a leader of the Fomorians, a group of malevolent supernatural beings, and considered the most formidable. He is often described as a giant with a large eye that wreaks destruction when opened. Balor takes part in the Battle of Mag Tuired, and is primarily known from the tale in which he is killed by his grandson Lugh of the Tuatha Dé Danann. He has been interpreted as a personification of the scorching sun, and has also been likened to figures from other mythologies, such as the Welsh Ysbaddaden and the Greek Cyclops.

Irish mythology is the body of myths indigenous to the island of Ireland. It was originally passed down orally in the prehistoric era. In the early medieval era, some myths were transcribed by Christian monks, who heavily altered and Christianised the myths. Irish mythology is the best-preserved branch of Celtic mythology.