—while I've enjoyed all the Smith episodes, I do feel the pacing has been a bit too fast lately). I am curious what others think so feel free to share your love, hatred, or indifference in the comments section.
What I really want to know is the identity of Missy. This is the woman who seemed to revive the half-face clockwork man at the end of the episode and informed him he had reached "the promised land". I am in the dark as much as anyone (in fact probably more in the dark than some of the real obsessive fans) but I have a few guesses.
The first possibility I thought was she is a future version or an alternate version of Clara. Missy did call the Doctor her boyfriend, and this is the episode where the Doctor emphatically stated "I am not your boyfriend" so there seems to be a possible connection there. Given the fact that Clara exists across the Timelord's timeline, this could be any of those versions of her. It seems likely she is the woman who gave Clara the Doctor's number, so there is that as well. She could also simply be Clara in the future, or in the future in another body or state (with Doctor Who you never know). Maybe things get very bad between Clara and the Doctor and in this is the future outcome.
The next possibility I thought of was this is Madame de Pompadour. There is clearly a connection between the clockwork men in The Girl in the Fireplace and the clockwork men in Deep Breath. But when the Doctor last saw Madame de Pompadour he had promised to show her a star and then returned after she died. Just before that she had seen into the Doctor's mind and knew what he knew. So with all that knowledge, it is entirely possible she came up with some clever way to meet him again after her death. She had quite a few years to work on a solution after the Doctor left. And it is also more than a little possible she has been changed for the worse by this process. Plus she does have valid reason for carrying some resentment towards him (though her letter in the end of The Girl in the Fireplace doesn't suggest resentment to me).
Obviously River Song is another possibility but if it were her, I'd expect she'd call the Doctor her husband, not her boyfriend. She could also be Tasha Lem, but I think she is actually River Song, so again, I would expect her to call him her husband. Though I could always be wrong about Lem's identity.
I've heard some folks say maybe it is the Master or even the TARDIS. I have to admit, neither of these occurred to me while watching, but some have pointed out that Missy, could be a shortened version of Mistress, which is a female Master. That seems pretty tight in terms of the name. I could also see the Master calling the Doctor his (I suppose in this case her) boyfriend for any number of reasons (most likely because he finds the idea amusing now that he is a woman---if Missy is in fact the Master). Something tells me though it isn't the Master. I suppose it could be the TARDIS. That feels a little strange. When the TARDIS did take human form she was certainly a bit off, but Missy seems a lot more sinister.
It is also possible Missy is an older character from the original series.
What are your theories on the identity of Missy?