Gelert

Gelert (Welsh pronunciation: [ˈɡɛlɛrt]) is a legendary dog associated with the village of Beddgelert (whose name means “Gelert’s Grave”) in Gwynedd, north-west Wales.^[1] In the legend, Llywelyn the Great returns from hunting to find his baby missing, the cradle overturned, and Gelert with a blood-smeared mouth. Believing the dog had savaged the child, Llywelyn draws his sword and kills Gelert.

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 overcome with remorse and buries the dog with great ceremony, but can still hear its dying yelp. After that day Llywelyn never smiles again.

Source: Wikipedia