Star Wars Episode III - The Voice of General Grievous
Here's what the official site said about the next great voice over:
"His implacable metallic skeleton gives him the aspect of a droid, but hidden inside the armored carapace is an unwholesome, living being. To remind viewers of this inner Grievous, his words are occasionally punctuated with a hard, wet hacking cough -- suggesting that Grievous is literally rotten to the core.
Providing the voice of Grievous is Matthew Wood, whose history with Star Wars has been mostly behind-the-scenes. Though Wood is an actor, his contribution to the prequel trilogy has been primarily as Supervising Sound Editor. His access to the Episode III production process may have given him a head's up that casting was underway for the part, but the use of a pseudonym ensured that insider status didn't factor into the selection process."
"In a three-hour recording session, Wood laid down all of Grievous lines. "He's definitely an evil character. He's the leader of the droid army, but not a droid. He feels things; he feels things extremely, I would say. It's a lot of yelling, and shouting out orders, so it had a lot of drill sergeant to it."
Source: Star Wars.com