Who is That Movie Deep Voiceover Man?

I just watched the ad for the DVD version of Transformers, another BIG DUMB movie. As a result, one question occurs to me. Who IS the man who does the voiceovers for ALL movie trailers and DVD ads? Is it just one man or are there a legion of them, all with the same gruff deep American voice? Can someone tell me?

Incidentally, the semiotics of the gruff, deep-voiced American voice are interesting. The deep voice is the voice of the tough-guy, but it's also paternal. The American accent denotes Hollywood authenticity, especially to a UK audience in the thrall of US culture. It seems irrational that there are no alternatives until you imagine someone else doing it. They just wouldn't seem as authoritative or exciting...