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.
'Devil in a Red Dress' by Maxine Price Painting Print
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.
Cŵn Annwn -- In Welsh mythology The Hounds of Annwn are the spectral red eared, white coloured dogs of the Wild Hunt. The Hunt is lead by Arawn or sometimes by Gwynn Ap Nudd who is both the King of the Fairies and the King of the Dead. It is said their growling is louder when they are further away and quieter when close and to hear their call is an omen of death.