Huan, the Great Hound, fight against Sauron in front of his tower. In this time Sauron is still just a servant of Morgoth, but shape his mundane form to a wolf and then to a snake to fight Huan, but the hound won him. Luthien is looking the duel. I take care do not show Luthien's face, because his beauty cannot be true reproduced. This is a scene from 'Beren and Luthiem', from Tolkien's Silmarillion.