Cliff-ghasts were approximately half the size of a grown human. They were capable of flight, with leathery wings, and had hooked claws. Their heads were flat and they had wide, frog-like mouths and bulging eyes. They gave off a foul smell.
Cliff-ghasts were scavengers, living off carrion.
Cliff-ghasts communicated with one another using spoken language, though they were not known to speak to other species.
Cliff-ghasts revered the eldest of their kind, a blind ghast whom they called Grandfather. He is respected as a source of knowledge and legend, whose memory goes back to before the existence of humans. This Grandfather predicts the 'greatest battle ever fought', that is the war against the Authority, and that Lord Asriel would win if he were in possession of the subtle knife, called Æsahættr in their tongue.