In The Shadow of Mordor, he is the main antagonist and leader of Sauron's forces in Mordor. He is known as the Master of Lies. He is the leader of the Black Captains and is very strong. He answers directly from Sauron. It is never know if he served Morgoth.
Unable to assume a fair form, Sauron's hand was blackened after the death of his body in the Fall of Númenor. When Isildur cut his ring-finger off with the shards of his father's sword, Sauron's one hand had four fingers.