The next inhabitant of the Tardis and David Tennant's replacement as Doctor Who will be announced this afternoon.
Tennant, currently recovering from back surgery, confirmed in October he would step down from the popular BBC1 show after filming four special episodes this year.
His successor, the eleventh Time Lord, will be announced in a Doctor Who Confidential special on BBC1 at 17:35 GMT.
Speculation is rife concerning the next Doctor and an ambiguous BBC statement did not dismiss the notion that Tennant's replacement may be a female actor.
The corporation said the actor would be giving "his or her initial reaction to being the new, 11th incarnation of one of television's most loved characters."
Executive producer Piers Wenger added: "We are so pleased to have been able to cast this person as the new Doctor.
"We believe the actor is going to bring something very special to the role and will make it absolutely their own - I just can't wait to tell everyone who it is - it has been a nail-biting Christmas trying to keep this under wraps!"
Actors linked with the part include Paterson Joseph - who would become the first black doctor - as well as Russell Tovey, James Nesbitt and John Simm.
However, writer and executive producer Russell T Davies has mooted the idea of a female Doctor, with Jennifer Saunders and Catherine Zeta Jones both thought to be in the frame.