8. Martha (And Mickey?)
In my opinion, Martha is the only contemporary character that could (and should) come back. Martha had the potential to be such a brilliant companion and sometimes that came through. Her sassy and intelligent introduction in 'Smith & Jones'. Battling against the conventions of class and race, while trying to protect the Doctor from his enemies in 'Human Nature' / 'Family Of Blood'. Traversing the globe to bring the message of the Doctor and defeat the Master in 'Last Of The Timelords'. I also love the fact that she chose to leave, a much more confident and worldly companion who didn't need the Doctor. Joining UNIT in season four was a brilliant move for Martha but sadly she never got a chance to play to her strengths. Immediately being captured and replaced with a Sontaran clone in 'The Sontaran Stratagem' / 'The Poison Sky' lost all that intelligence and strength that made her so good in the first place and turned her into a damsel in distress. It wasn't the same Martha that saved the world in series three. Her best episodes post-series three were in Torchwood series two, well the first episode at least. Martha got lost in the mix in the second and third stories as Owen's resurrection took centre stage. That being said, I wish they'd been able to bring her back full time for series three and four...though knowing that series, there's a 50/50 chance we'd have witnessed her death by now. Instead...she married Mickey. I guess that one scene they shared at the end of 'Journey's End' was the start of something new... Post UNIT and Torchwood, who is Martha now? She's still saving the world, Mickey at her side, as suggested in 'The End Of Time'. It's almost odd that the Doctor hasn't run into her again. So perhaps, when Doctor Twelve faces the next alien threat to Earth, what about a return of the woman who helped him defeat the Master? Better still, if we have the Master in series eight, now might be the time for Martha to take action again. Of all the companions in Nu Who, she has the biggest connection to this long-standing enemy of the Doctor. It would be a shame to squander that.