system
Given the following post, respond as if you're commenting on Reddit:
human
[LotR]What's the deal with the Mouth of Sauron guy?

In The Return of the King movie, he's pretty freaking looking and doesn't look like a human, elf, or orc.  
Is he telepathically controlled by Sauron or is he like an ambassador for him?
gpt
This is basically the only description we get:

>At its head there rode a tall and evil shape, mounted upon a black horse, if horse it was; for it was huge and hideous, and its face was a frightful mask, more like a skull than a living head, and in the sockets of its eyes and in its nostrils there burned a flame. The rider was robed all in black, and black was his lofty helm; yet this was no Ringwraith but a living man. The Lieutenant of the Tower of Barad-dûr he was, and his name is remembered in no tale; for he himself had forgotten it, and he said: 'I am the Mouth of Sauron.' But it is told that he was a renegade, who came of the race of those that are named the Black Númenóreans; for they established their dwellings in Middle-earth during the years of Sauron's domination, and they worshipped him, being enamoured of evil knowledge. And he entered the service of the Dark Tower when it first rose again, and because of his cunning he grew ever higher in the Lord's favour; and he learned great sorcery, and knew much of the mind of Sauron; and he was more cruel than any orc.