Doctor Who: 12 Cool Details Russell T Davies Just Revealed About New Earth & Gridlock
7. Captain Jack Harkness Is DEFINITELY The Face Of Boe (And This Is Why He Looks Like A Giant Head)
Just in case there was still any doubt, Davies has now fully, unequivocally put that doubt to bed: Captain Jack Harkness is the Face of Boe.
During the scene where Boe disappears at the end of New Earth, the writer simply tweeted "And Captain Jack fades away".
This is an odd situation, because while the show makes it pretty clear that Jack and Boe are one and the same (Jack literally calls himself the Face of Boe at the end of Last of the Time Lords, and also, how else would Boe know that the Doctor isn't alone?), some people didn't believe it, and this idea has been floating around in "fan theory" territory for over a decade, depending on who you ask. But now, it's undeniable.
In a separate tweet, Davies also explained why Jack ended up looking like Boe, stating that, after five billion years of growth, "extraordinary changes" took place physically.