7. Wesley Crusher
Oh stop it. You all like Wesley. With his annoying habits (like saving the day) and the way he was written as if all the writers secretly wanted to be him... Ok Wesley was not everyone's cup of tea. That's for sure. Just look at the newsgroup alt.wesley.crusher.die.die.die. But we're not talking Wesley Crusher from the first few seasons of Star Trek: The Next Generation here. We're talking the Wesley Crusher that has gone off with the traveller and seen what is out there and has come back to warn Starfleet. He's now played by the Wil Wheaton that we've all seen and loved in the Big Bang Theory. The Wil Wheaton who regrets being a little jerk as Wesley and wants to redeem himself. The Wil Wheaton who should still be annoyed at getting cut from Nemesis. That Wesley Crusher and that Wil Wheaton. As I said, Wesley could come back to warn Starfleet and be stripped of his traveller-like powers in the process. He joins the crew to seek out the enemy that he knows is out there and effectively be the Neelix of the show (in a less chef-like and please, please, please, less irritating way). There would be outcry from the fans, but Wil Wheaton isn't 14 anymore and neither is his character. I think he would be a fantastic addition not only to the show but to the main cast he is after all, a fan of Star Trek now himself.