Ever since it was announced months ago that actress Michelle Gomez would be making her Doctor Who debut in the two-part series 8 finale Dark Water / Death in Heaven, fans have been wild with speculation as to who this chick really is. A press release billed her character as the “Gatekeeper of the Nethersphere,” which to many seemed a title meant to throw us off. But in a surprise cameo twist, Michelle Gomez appeared at the tail end of the series opener, Deep Breath, and the subsequent episode Into the Dalek. If the initial spark wasn’t already enough, the internet’s been set ablaze by the fan theories. More so than I can realistically cope with. I’ll try and sift through my favorite theories.

But first it’s important to note something Moffat mentioned the day before Deep Breath aired, in a BBC interview: “We’ve got some cracking new monsters – the Teller. And we’ve got some cracking old monsters – the Daleks will be back. Another major foe will be making a return, but more of that later.” Now note that in the video provided, he doesn’t actually tell us which “major foe” he’s referring to and he could be referring to a certain shiny monster that will appear in the season finale (that I won’t name due to spoilerphobes). This has likely spurred rumors on further.

Let’s first take a step back and look at what we’ve been provided thus far as to her true nature (and mind you, it isn’t a whole lot). Both appearances occur in a place she dubs “Heaven,” or “Paradise,” and both appearances narratively occur right after someone’s perceived death. Those characters who perish also show up in their respective episodes. She calls herself “Missy,” has a frightening smile, and other enigmatic tendencies. We are also strongly led to believe that she was the one that put the “Impossible Girl” ad in the paper, and that she initially led Clara to the Doctor in The Bells of Saint John as the “woman in the shop”. Let’s get right into some theories (many of which are personal ponderings), but I’ll spare you some of the less likely theories, such as how she is actually the TARDIS, Clara, or River Song.

The Master
The prevailing theory is simple. Her name is “Missy,” which could be short for Mistress, which is the gender opposite of Master. Is this a bit of a stretch? Nothing’s too big of a stretch when it comes to fan theories! I personally don’t care to see the Master back any time soon, but won’t be disappointed if it is the Master and is done well.

The Rani
When I first read the script for Deep Breath a while back my first thought when they brought Missy in was “Gasp! They’re bringing the Rani back!” This theory’s only real argument is that Michelle Gomez is a woman, and has those strong, makeup-caked features prominent in the previous Rani. The Rani, for those unaware was a renegade Time Lady who first appeared in the 6th Doctor serial The Mark of the Rani, and subsequently in the 7th Doctor’s debut Time and the Rani. Played by Kate O’Mara, who sadly passed away earlier this year, the Rani literally meant “the Queen”. I think she’d be a terribly interesting character to bring back, as she was never given the proper chance to appear in a decent story.

Romana
Another Time Lady, and former companion of the 4th Doctor, it is unlikely that Missy is actually Romana. But Missy does claim to know the Doctor, asserting that he is her boyfriend. (Not that the Doctor and Romana were ever an onscreen thing). Romana I played by Mary Tamm, and Romana II played by Lalla Ward are equally beloved companions, and unlikely enemies – Missy is most certainly the overarching villain this season.

The Black Guardian
This is one I’ve personally been pondering, and have seen others on Twitter in agreement. The Black Guardian is the anthropomorphic personification of the dark forces opposed to the powers of light, as personified by the White Guardian. The Black Guardian, surprisingly, isn’t rumored about returning fairly often. I don’t know why though. He played a huge part in two classic seasons involving the 4th and 5th Doctors. In his last on screen appearance he warned the Doctor that he would return to threaten his life a third time – we’ve yet to see that third time on screen. (I’m sure Big Finish has nabbed that by now though). He dresses all in black, similarly to Missy, and has a dead crow on his head (not dissimilar to her current hairdo). What’s more? He is also known as the “Guardian of Darkness and Chaos” which sounds eerily similar to “Gatekeeper of the Nethersphere”. Probably not going to be the case, but c’mon! He’s gotta return for a third go around at some point – and Moffat has mentioned he’s a big fan of the Davison era.

The Valeyard
The Valeyard’s only appearance was during the Trial of a Time Lord season in the 6th Doctors era (a guilty pleasure of mine to be sure, as it’s rarely looked back fondly upon). He is, according to the Master, “an amalgamation of the darker side of the Doctor’s nature,” and is supposedly an offshoot incarnation between his 12th and final regenerations. As The Time of the Doctor made clear, the numbering is irreversibly screwed, seeing that John Hurt’s War Doctor is the real 9th, and David Tennant’s 10th sucked down an extra regeneration, making Capaldi the 14th regeneration (but still the 12th Doctor). It’s likely that somewhere along the lines The Valeyard’s slipped loose. Perhaps he’s taken on the shape of a woman this time around. Perhaps this Heaven is all in the Doctor’s subconscious waiting to be set free along with the Valeyard. The Valeyard was even mentioned in The Name of the Doctor in a passing line, so it’s clear Moffat hasn’t entirely forgotten about him. And let’s not forget that Missy has the Doctor’s number (if she really is the woman in the shop).

Of course, we may all be looking into this far too much. But that is the way of things when you’re a fan of the series. Perhaps it’s just a new villain with some sinister ability to reanimate the dead. Moffat’s tease of a major foe may just be referring to another recurring monster.

Can we expect to see more of Missy, aside from her credited role in the finale? I think so. If you’ve noticed, there are several upcoming episodes that Moffat is credited as co-writing (something he’s never done in the past). That includes yesterday’s Into the Dalek. What this is telling me is that the majority of the episode is being written by the other writer, while Moffat is squeezing in a scene or two to expand his ongoing arc with the Gatekeeper of the Nethersphere. If that’s the case, we can expect to see Missy return in at least episodes 4, 5, and 6.