Gelert is the name of a legendary dog associated with the village of Beddgelert (whose name means "Gelert's Grave")
in Gwynedd, northwest Wales. The story of Gelert is a variation on the well-worn "Faithful Hound" folk-tale motif, which lives on as an urban legend. It is classified as Aarne-Thompson type 178A.
Here, the dog is alleged to have belonged to Llywelyn the Great, Prince of Gwynedd, a gift from King John of England. In this legend, Llywelyn returns from hunting to find his baby missing, the cradle overturned, and the dog with a blood-smeared mouth. Believing the dog savaged the child, Llywelyn draws his sword and kills it. After the dog's dying yelp Llywelyn hears the cries of the baby, unharmed under the cradle, along with a dead wolf which had attacked the child and been killed by Gelert. Llywelyn is then overcome with remorse and he buries the dog with great ceremony, yet he can still hear the dying yelp. After that day Llywelyn never smiles again.