Doctor Who's Matt Smith has officially wrapped his last episode as the iconic Time Lord while Steven Moffat works to ensure that Peter Capaldi won't be one of the last regenerations.
Smith ended his tenure as the 11th Doctor on Oct. 5 following the completion of filming for the Christmas Special.
"So it's goodnight from me, and it's goodnight from him. That's a wrap. Christmas 2013. Thank you all," tweeted producer Marcus Wilson.
Smith's mother, Lynne Smith, also tweeted the above photo of herself and her son on his last day inside the TARDIS.
As the BBC sci-fi series moves to introduce the 12th Doctor during the Christmas Special regeneration sequence, the current showrunner is working to circumvent a previous rule that limited the number of regenerations any particular Gallifreyan was allowed.
The 12-regeneration cap (which allows for 13 iterations of the Doctor) was first introduced in the 1976 episode "The Deadly Assassin," which was penned by Robert Holmes and featured the Fourth Doctor (Tom Baker). Now, if the series wants to continue past Capaldi, this rule must be altered.
This is assuming that the Unnumbered Doctor (John Hurt), who will be featured in the 50th Anniversary Special "The Day of the Doctor," will actually count as a numbered regeneration.
"I know people are worried about it, but I think there will be a way around that rule," said the Fifth Doctor, Peter Davison, according to the Telegraph. "I know that Steven has put in the groundwork already in an episode so that there can be more."
"The Day of the Doctor" will air on Nov. 23 and will be simulcast around the world. The Christmas Special will air on Dec. 25.