9. Tom MacRae
Other than the fact that he has positively increased your fear of upgrading things to their "next levels", he also introduced Cybermen to NuWho in a very horrific but remarkable way. He gave Mickey a reason to stop being the "tin dog" and gave way to Pete's World, without which Rose would probably be dead (or, if you'e anti-Rose, he turned her into a dog, which is more than you could ask for). If that wasn't enough, he also turned Rory Williams into the man of your dreams (as if he wasnt already!) and broke a billion time travel rules in the most perfect way possible, despite the minimal budget and leaving the viewers with a ton to piece together by themselves. It's all a matter of good writing, of course, which Tom does not do.