Cafall is Bran Davies' dog, a black and white sheepdog with silver eyes. He is referred to in the Grail verses as "the silver eyes that see the wind," and he was always able to see things that others could not. He found a lost Will Stanton on a hillside on Cader Idris, kept him from falling, and provided the trigger for Will to remember his mission as an Old One. He was shot by Caradog Pritchard, acting as an agent of the Dark.
In Arthurian mythology, Cafall was the name of King Arthur's dog, though it is worth pointing out that cafall is also an old Welsh word for "horse", probably derived from the Latin caballus, meaning "packhorse".