River Song - the Doctor's Wife. Time traveller, adventurer and played by the delightful Alex Kingston. Now Alex Kingston is an excellent actress. I have no problems with her appearing in Doctor Who and she brings a lot to the role. If only the role had a lot to offer her.
Let's be honest, in her first appearance, she was brilliant. She was someone you could see as the Doctor's equal. She was intelligent, action oriented and held her own. Her sacrifice at the end was well thought out and if that had been the last we had seen of her, in setting up the next season's plot arcs it would have been great.
And then we get her back again...again...and again.
The main problems I have with River Song is that they make her out to be a good, strong person. Good, strong people do not torture and kill helpless alien beings. In terms of being the Doctor's Wife, apparently they love each other but spend all their time apart. They are about as dysfunctional a couple as you could get. I'm not even sure the Doctor shows any love for her at any point. He seems to be spending more time with his latest young female companion who he has known since they were really young. Oh wait, he's known River Song since she was born...
And finally, there are two other people who really need to be mentioned. Bernice Summerfield and Ace. You want excellent strong female characters in Doctor Who, go look at these two instead.