Nazgûl

He roams as a silent knight, he is wise in his own darkness, lurking in the shadows as a spectre

Has the appearance of a rather tall man, with oth a heavy and willowing dark cloak, old and greyish, that hids an intrinsic silver armour.
Underneath it all he has long onyx colored hair, pale skin, greyish, almost white eyes, pointy ears and sharp canines.

Him and the Nazgûl were nine men, three of whom were great Númenórean wizards and warriors . The Dark Lord Sauron offered each of them a Ring of Power, which led to their downfall.
they suffered changes in appearance, at times becoming invisible, and an evil grew ever stronger within them. Completely invisible and corrupted by Sauron , chained to his will, the Númenóreans fled north.