whos knocking at the doctor

It is returning, it is returning through the dark ... he will knock four times." The psychic lady on the 200 bus said these darkly prophetic words to The Doctor during the conclusion of 'Planet Of The Dead', whipping up the tension ahead of David Tennant's impending departure. But who exactly wants to get in touch with The Doctor?"


Their list includes:

The Face of Boe
Ood Sigma
Dalek Caan
Grim Reaper
Captain Jack
Bad Wolf
Wilf
The Drowned Hath
The Master