All of these well-known actors, and more, were rumored to be playing big roles in EA Mythic's in-development title. Discussion of these actors has been swirling through WAR forums for a few weeks, and was repeated on a popular Warhammer-related podcast. Certainly, with EA backing the game's production, it doesn't seem out of the question that such A-list celebrities could be corralled for contributions. Most of them have already done voice work in games before, making it all the more likely. For confirmation Massively contacted a press representative that works with the company. We recieved this humorous response in return: "We looked into this voiceover talent list, and it is not true. Sorry to disappoint! WAR will definitely have high-quality voiceovers, but no Jack Black."
More's the pity, but best to keep everything clear just the same. Thanks to Eddiemae Jukes for setting the record straight. Just to complete the set, other rumored contributors included Michael Ironside as the Dwarven leader Thorgrim, and Ian McKellan as the Phoenix King (the High Elven leader). It's nice to dream, huh?