Doctor Who is to strain the space-time continuum by appearing in more than 70 countries simultaneously - as the show's 50th anniversary special is simulcast around the world.
Tens of millions of people around the world will watch the global premiere of The Day Of The Doctor - which will star Matt Smith and David Tennant - when it is screened on November 23.
In addition to numerous TV networks broadcasting the programme at once, it will also be shown in cinemas, many of them in 3D under deals struck by BBC Worldwide, the commercial arm of the corporation.
Steven Moffat, the executive producer of the episode, said: "The Doctor has always been a time traveller - now he's travelling time zones.
"On the 23rd of November, it won't be the bad guys conquering the Earth - everywhere, it will be the Day of the Doctor."
In addition to Matt and David playing two regenerations of The Doctor, Jenna Coleman will be playing Clara Oswald and Billie Piper will reprise her role as Rose Tyler. And John Hurt is to play a further regeneration of The Doctor who has only previously been glimpsed at the climax of the most recent series.
So far 75 countries have agreed to screen the show including Canada, Brazil, Botswana and Burma. More than 200 cinemas around the UK will be showing the episode.
Tim Davie, chief executive of BBC Worldwide, said: "Few TV shows can still lay claim to being appointment viewing but Doctor Who takes this to another level.
"In its 50th anniversary year, we wanted to create a truly international event for Doctor Who fans in as many countries as possible and the simultaneous broadcast and cinema screening of the special across so many countries will make for a fitting birthday tribute to our Time Lord."
Other events to commemorate the anniversary include a Doctor Who celebration at London's ExCel in east London which is expected to draw more than 20,000 fans, with familiar faces such as Smith, Sylvester McCoy, Colin Baker and Tom Baker among the guests who will gather.