7Ben & Polly
Played by Michael Craze and Anneke Wills
Ok, I'm totally cheating here by putting two in one spot, but you really can't have one without the other. They come as a pair and I don't think either would have been so good, fun or interesting if they appeared seperately. They made each other great.
It's a travesty that they only have one complete serial surviving and only a handful of orphan episodes, but it's a sign of how great they are that they managed to make my list through mostly audio alone. On screen, in what I have been able to see of them, they are even better and the chemistry between them is brilliant. They seem as pefect examples (to me, who wasn't there) of the swinging 60s, and from what I've heard of Anneke Wills, that wasn't such a stretch as she was very much the scene queen.
Unfortunately, Michael Craze passed away, but Anneke Wills is alive and kicking and still a huge part of the show and fandom and I would love to see her on the show again. It's unlikely, of course, but it would be amazing.