Mother Una is a legendary figure who appears in the tale The Siege of the High Reaches, the first story of The Ádairiad, a collection of epic poems in Áes Camáir folklore penned by an ancient bard, Gwytheon.
In the tale, Mother Una was granted use of the Croccán dé Túirenn by the goddess Bráenna ap Túirenn, that she might save her people from starvation when goblins besieged their mountain fortress. When the siege ended in the spring, Mother Una passed away that very night, her mission done, and the Croccán was taken back by Bráenna.
Mother Una is revered as a saint or a demigod: unable to grant divine spells to priests, but prayed to as someone to can intercede with the gods on the supplicant’s behalf.