Tylwyth teg is a common Welsh name for fairies, which means "the fair folk." Sometimes called "bendith y mamau" which means "a mother's blessing" and is a euphemism for these fairies in Glamorganshire. Their king is said to be Gwyn ap Nudd. They are associated with the lake, Llyn y Fan Fach in south Wales.
Calling fairies by a favorable name "fair folk" or "mother's blessing" was hoped to avert kidnapping in which the faeries would typically leave a sickly changeling child in the place of the healthy child they had stolen.
These fairies were described as fair-haired and as loving golden hair. They were said to covet mortal children with blond or fair hair. They are usually portrayed as benevolent but capable of mischief. They are neither entirely good or completely evil, unlike the Selee and Unselee (See also seelie and unseelie.) In their benevolent capacity, they might, for example, reward a woman who kept a tidy house with gifts of silver.
The Tylwyth Teg are said to fear iron and unbaptized children could supposedly be protected from them by placing a a poker over their cradle.
Gwlad y Tylwyth Teg is a Welsh name for fairy-land.