Matt Smith is due to regenerate in this year's Doctor Who Christmas Special following the events that take place in the 50th Anniversary episode due to air this November.
What could be Smith's last Comic-Con - at least as Doctor Who - the actor answers a question on why he decided to make the change in his life.
Below you can check out video of Matt Smith answering the question why he is leaving Doctor Who.
And speaking of a new Doctor, showrunner Steven Moffat is also asked about the online rumor that the 12th Time Lord could be a female, in which a rather funny response follows.
The Doctor Who 50th Anniversary airs November 23rd featuring John Hurt as "The Doctor" and also stars Jenna Coleman as Clara.