[Boromir88]

jordainian, if you haven't seen ROTK EE you would not be familiar with the Mouth of Sauron. Jackson adds him in the EE.

He is Sauron's herald and ambassador. Lieutenant of Barad-dur. His main purpose in LOTR, as seen was to deliver to Aragorn and co. at the black gate the mithril shirt they found and claiming that their attempt had failed and the poor hobbit Frodo was tortured and killed. He then delivered terms Sauron offered for the everyone to submit to Sauron and pay tribute to him, of course Aragorn denied.

The Mouth was said to be a black Numenorean taken in by Sauron, grew in his favor, and taught him a bit of sorcery. That's really all that's said on the guy. Hope that helps. If you really want to see a good depiction of the Mouth of Sauron I suggest reading the books, instead of watching the movies, because Jackson's movie version I don't think shows too well the Mouth of Sauron's true purpose, to be a messengers. Which was to offer the terms that Sauron gave. He would spare their lives if they submitted fully to Sauron.