i would say number 4?

i don't know why...but it would be much better if she's his mother then she can't marry him thank goodness :P

another one thats most likely is probs no 1?? cause she does seem a bit evil at times

I think/hope she's only a sort of companion type thing. A clingy one but a future companion and one he gets close too (for some reason) but I think she'll get closer to him than he ever will to her.

A tacky garden gnome he saved one time making her get clingy... obvs :P

^scratch my diea that is sooo what she is!!

SPOILERS!!!!!!

LOL.

I honestly think she is his wife... I don't know she just acts liek it and the look in forest of the dead was funny and very telling... plus she reminds me of a mix of Rose and Amy the two he seems to love most... and definitely most romantically

Ew , I don't think she's his wife ^^ She's like so old looking for him!

Yes but we're seeing her AFTER she met the doctor whoes to say she wasn't young when she met him and just lived life

me and my dad thought that she was number 4!

SPOILERS! in other words I have no idea!

haha! Thats probably what River means when she says it. She probably doesn't know anything.

I would have said a future companion, maybe romantically, but of course the Doctor doesn't know that yet. XD

she must be evil or something because before she killed the dalek in the big bang the dalek seemed really scared of her and begged for mercy which is something a dalek never does and she killed it anyway.

^ yeah i noticed tht too...

i think she is either the doctor's wife or she is one of his enimes because she killed someone and she it was the greatest man she's ever know. now who could that be???xx

Right I've changed my view due to watching series 6 trailer so spoilers ahead ppl!
I think that she is simply the doctor's hats killer! Every time he gets a hat, BANG! she kills it. First the Fez (RIP) and now she's going to be shooting his stetson! What is wrong with her?! >:( *mutters angrily*

^ My god, I know! I mean, first he looks adorable in a fez. She shoots it. Then he gets a stetson. He looks hot! Then she friggin shoots that too. DX

^I KNOW RIGHT! Grr that woman! D:

4 is probably the most likely. I hope its not 3 because Amy needs to be with the Doctor!

ummm can I just say.... in the commentary Steven Moffat said she wasn't his mother... there was too much sexual tension! I still say she will be his wife... in some really complex way... my inner fan-girl says she is a regeneration of Donna......., but that's my fangirl