Cave beasts are a species of humanoid creatures in the Cthulhu mythos.
They are described as a white humanoid creatures with claws and fangs. "Its hair was snow-white, a thing due no doubt to the bleaching action of a long existence within the inky confines of the cave, but it was also surprisingly thin, being indeed largely absent save on the head, where it was of such length and abundance that it fell over the shoulders in considerable profusion."
"From the tips of the fingers or toes long nail-like claws extended. The hands or feet were not prehensile, a fact that I ascribed to that long residence in the cave which, as I before mentioned, seemed evident from the all-pervading and almost unearthly whiteness so characteristic of the whole anatomy. No tail seemed to be present."
"They were black, those eyes, deep, jetty black, in hideous contrast to the snow-white hair and flesh. Like those of other cave denizens, they were deeply sunken in their orbits, and were entirely destitute of iris. As I looked more closely, I saw that they were set in a face less prognathous than that of the average ape, and infinitely more hairy. The nose was quite distinct."
"The creature I had killed, the strange beast of the unfathomed cave was, or had at one time been, a MAN!!!" H.P. Lovecraft, The Beast In the Cave