I think its safe to say that the Curator presented in The Day of the Doctor is one of the most intriguing of surprises, and certainly one that is to fascinate for quite some time.
However, its not certain as to what exactly
he is. So I thought we could dedicate a discussion for this.
Do you think he could be the Nth Doctor? The Last-Ever Doctor? If that is the case, then the rumors that have Peter Capaldi's Doctor be the first Doctor of a new cycle would certainly be false, because the Eleventh might be expecting to regenerate into a Fourth Doctor-like Doctor again, after seeing him there.
Could he be the Fourth Doctor that, perhaps during the time period between The Invasion of Time
and the Key to Time arc, he aged and even took the job of the curator being being somehow rejuvenated to a younger state, and resumed his adventures with the Key to Time arc? As much as I like the idea of him being the Fourth Doctor, just older, it doesn't quite make sense.
A few posters noticed the face picking arc that might permeat the Twelfth Doctor's first series, and that got me thinking... Rather than the Doctor just choosing the Fourth Doctor's face again in the foreseeable future, could he actually be the face that one of the first three Doctors saw one time, long ago, and thus inspired
the Fourth's appearence? After all, he did say "I never forget a face".
What do you all think?