It is nearly time for Doctor Who fans to both celebrate and to mourn.
The former because this beloved British series airs its annual Christmas episode on December 25... but the latter because it will mark Matt Smith's final appearance in the iconic title role.
What will cause Smith to regenerate into Peter Capaldi? We can't say at the moment.
But a new trailer for "The Time of the Doctor" features the return of a few old friend and also many old enemies, all of whom have it out for the Time Lord.
Watch Doctor Who online to catch up on anything you may have missed and view the extended teaser now: