Editing Biróg (section)

== Attestations ==
{{main|Glas Gaibhnenn}}

A version of the folktale recorded by [[John O'Donovan (scholar)|John O'Donovan]] in 1835 relates how the [[Fomorians|Fomorian]] warrior [[Balor]], to frustrate a prophecy that he would be killed by his own grandson, imprisons his only daughter [[Ethniu|Eithne]] in the tower of [[Tory Island]], away from any contact with men.

But Biroge of the Mountain helps a man called Mac Cinnfhaelaidh (Mac Kineely), whose magical cow (Glas Gaivlen ''recté'' [[Glas Gaibhnenn]]) Balor stole, to gain access to the tower and seduce her. Eithne gives birth to triplets, but Balor gathers them up in a sheet and sends a messenger to drown them in a whirlpool. The messenger drowns two of the babies, but unwittingly drops one in the harbour, where he is rescued by Biróg. She takes the child back to his father, who gives him to his brother, [[Goibniu|Gavida]] the smith, in [[fosterage]]. The boy (identified in the tale only as the "heir of Mac Kineely") who grows up to kill Balor,<ref name=odonovan/> is more explicitly identified as [[Lugh]] in Lady Gregory and [[T. W. Rolleston]]' retelling.<ref name=gregory/><ref name=rolleston/>

Lady Gregory refers to her as Birog the druidess, and [[T. W. Rolleston]] gives her orthography as Biróg.<ref name=gregory/><ref name=rolleston/>