Also my nominations go to:
1. David Kaye, the Megatron of my childhood. Beast Wars, Beast Machines, and the Unicron shows, he was unmatched.
2. Corey Burton in animated. He had a really nice no-nonsense sinister Megatron voice and I love it.
3. Frank Welker. Yes, he's a great actor, but his G1 Megatron was kind of lame. Prime Megatron was fantastic, however. But he ranks so low on this list because I have to consider all of his interpretations and compare them to the other actors.