I know, I can't believe it either. Apparently they are just brief appearances in the first episode airing next Saturday, but it's said to open up the opportunity for more in the future.
Hit the jump for a brief description of their unexpected, insanely awesome return with a quote from BBC and some pictures from the upcoming premiere.
There will also be a few familiar faces in the first episode, with former stars Billie Piper, Freema Agyeman and Catherine Tate all taking on cameos.
Despite their return to the set, it will be their first screen venture with Smith, having played sidekicks to ex-Time Lord David Tennant.
A BBC source said: 'They don’t have a big part to play, but fans will love to see them return and they are trying to help Matt in an hour of need.
'It is a humorous scene and it opens the door to any of them if they wanted to come back and do some more filming in the future.'
I am kind of freaking out.
|What the what?? Some strange Mother-Daughter bonding?|
|I believe the English call this 'snogging.'|
|Clearly an alien techojellyfish.|
Can you stand it? I honestly never thought any of the old companions would return, much as I fantasized about seeing Rose and Donna again, in a not-cheesy Russel T. Davies lets-all-fly-the-TARDIS scene. And the cameo of Donna in Tennant's final episode was dissappointingly small. God bless you Stephen Moffat.