SONTAR-Whaaaaa???
After Doctor Who Executive Producers Piers Wenger told Crave Online that there would be a focus on new monsters in Series Six in response to a question about classic monsters returning, it seems at least one classic monster has a stratagem in place for their return appearance...The Sontarans.
The spud-headed clone warriors were last seen as part of the major alien alliance in the Series Five episode "The Pandorica Opens" and according to Doctor Who TV, were recently photographed at an outdoor filming location for what is believed to be Episode Seven of the upcoming series. The pictures above only show one Sontaran, so it's not known if there will be others or if this means that the alien alliance will also be returning.
This news follows on persistent rumors that the Cybermen will be returning as well, only these will be the traditional Mondasian Cybermen not seen in Doctor Who since "Silver Nemesis" in 1988. Curiously, these rumors suggest the Cybermen will also be in Episode Seven, so either that's not the case or there's a reformed alien alliance of some sort.