Oh come on, folks. I agree, James Earl Jones would be in the top, but think Casey Kasem, the guy who did American Top 40 for years and was the voice in many, many cartoons like the voice of Shaggy in Scooby Doo.
These are all such great answers. I think my vote would be a tie between James Earl Jones and Morgan Freeman.
Although, everybody knows Don LaFontaine's voice. You're probably thinking "Who?", but he's the guy who narrated almost all movie trailers. ((let it sink in)) Yep, now you know who I'm talking about. ;-)