7. The Master
The last time we saw the Master, it was during a brief reappearance of the Time Lords during The End of Time. As they disappeared, returning to the time-locked Time War, so did the Master, implying that he has been locked with them. So, with the Time War being explored again in this anniversary episode, there’s an opportunity here to revive one of the Doctor’s greatest foes.
The campaign to cast Benedict Cumberbatch starts here…
