In Welsh mythology and folklore, Cŵn Annwn were the spectral hounds of Annwn, the otherworld of Welsh myth. They were associated with a form of the Wild Hunt, presided over by Arawn, king of Annwn. They are often depicted as white with red ears.
Arawn Celtic god of the Otherworld found in the Welsh Mabinogion. He rounds up the souls of the dead in the Otherworld with his hounds (notable for their red ears and white bodies). Portrayed as a badass in modernity stemming from "our" religious construction of good and evil designed to taint the reputations of the Celtic/Pagan gods. On occasion Arawn is aligned with the Tuatha De Danaan and is said to have married into the Irish tribe. He may be Donn the Irish god of the Otherworld.
Gwyllgi Welsh Mythology Think of this creature as the faerie dog’s demonic, scarier, and darker cousin. All of Britain has legends of black dogs that portend certain doom, but Wales has one with a much better title—the dog of darkness. As with all scary, black, ethereal dogs, they are said to haunt lonely country roads and scare the living daylights out of travellers. The dog’s appearance is said to be a dark omen.