He’s still holding out hope that the Zygons might somehow make a return visit (mainly to bump up the release of the classic Tom Baker serial with the villains in the DVD release queue). And while they’ve been rumored to appear in every series since the show returned, there aren’t any rumors of them coming back this year.
However, that doesn’t mean some classic “Who” villains aren’t on the rumor mill.
Several rumor sites and discussion boards are saying the Cybermen will return in series six. But not the Cybermen we saw in the Russell T. Davies era, which heralded from a parallel universe. These would be the original Cybermen from the original series run. Nothing has been confirmed yet, but writer Steven Thompson, who worked with Steven Moffat and Mark Gattis, is reportedly working on a story with the metallic adversaries. Rumors say it could be set in Egypt and it would be the seventh and possibly eight episodes of series three. (That means we wouldn’t see the Cybermen until next fall).
Another possible old-school villain set to return in the Mara. Feature in two stories in the Peter Davison era, the Mara was an incarnation of human desire and darkness, which takes the form of a snake and controls people through tattoos on their arms. This rumor is fueled by set photos showing Amy and River Song with similar tatoos on their arms (though they look nothing like the original Mara marks from the Davison era) and the fact that the original Mara stories will get a box-set DVD release in 2011.
Another interesting rumor is that the two-part season premiere, currently filming in the United States, may feature a future version of the 11th Doctor and continue Moffat’s streak of playing with the time travel nature of the show. According to rumors, this Doctor will show up and reveal something about the Doctor’s future to Amy and that River will beg Amy not to tell the Doctor. This might all play into earlier hints from Steven Moffat about Amy having a big secret and episode seven revealing “the true nature of [The Doctor's] relationship with Amy Pond.”
Moffat also hints that the mid-season finale will offer flashbacks to “Genesis of the Daleks” and events that unfolded there. This classic serial is a pivotal one to the new series and former producer Russell T. Davies has confirmed that this was one of the first shots fired in the Time War. So, if you’ve not seen it, you need to do so immediately. It’s available on DVD to either buy or via Netflix.
Moffat also says all the questions left unanswered in the end of series five will be addressed in series six.
“All the answers are coming, I promise – including the answers to questions people haven’t even thought to ask yet. I mean, we know how Amy remembered the Doctor. But how did River…?” he says.
Of course, all of these are just rumors and speculation at this point. If you want to see more, check out Galifrey Base’s thread on the rumors surrounding the upcoming holiday special and series six.