I'm not sure that I'd classify any of these folks as major actors, though they're known to fans of particular shows. I watch a decent amound of movies, and I've never heard of any of these people other than Billy Dee Williams (and only because of Star Wars) and Michael Ironside.

Even still, it's interesting to see that a game company is getting real actors for a game... though it -is- EA, which would be the company that could afford it. After all, they're making tons off of selling games AND in-game advertising via spyware included with them.