The Bendith Y Mamau ("The Mothers' Blessing") is a rather unpleasant clan of Welsh fairies. They steal children and substitute them for their own ugly ones, called Crimbils.
Traditionally belonging to the Unseelie Court of Carmarthenshire (Wales, Bendith Y Mamau means 'the mothers blessing' and has become a generic name for the fairies, especially in Southern Wales. The other name for the fairies in Wales is the Tylweth Teg meaning the fair folk.
Bendith Y Mamau are most readily identified with the Brownies, or the West Country Pixies, although also regarded as the result of interbreeding between goblins and fairies.
Mothers had to take precautions not to leave their babies unattended in fairy country as Bendith were particularly ready to steal small children and replace them with their own changelings known as Crimbils.The Bendith envy beauty, and are sometimes consumed by jealousy, but they generally treat their captives well.
They would raise the child, teaching it of music and song in an extended Reverie, only returning the child much later, with only faint memories of sweet music. It was thought that they needed to improve their stock with mortal blood. The Bendith are also known to be astounding brilliant musicians and singers.
- There were various methods of retrieving mortal children from the clutches of the Bendith Y Mamau, many of them barbaric to the poor child suspected of being a Crimbil. Through the intervention of a witch, the parents can regain the stolen child, who will remember nothing of its time with the Bendith Y Mamau, except for a vague recollection of sweet music.
- Calling the fairies by the flattering title of the 'Mothers Blessing' was thought to appease them.
The Card Game Magic: The Gathering uses changelings in their Lorwyn block of cards. Specifically, the card "Crib Swap" features exchanging human children for the crimbil (though only the term changeling is used).