In December 2009 and January 2010, Doctor Who put out two episodes with the same title for the first time in the 2005 revival.
The End of Time Part One aired on Christmas Day 2009, with Part Two coming a week later on the first day of 2010. This primetime scheduling was only fair, as these two episodes marked a significant shift in the show's makeup.
Not only was it the end of David Tennant's Tenth Doctor, who regenerated at this two-parter's climax, but it was also the final episode to be helmed by Russell T Davies (at the time!), the man who brought Doctor Who back from cancellation.
With all that going on – plus the Master's return, his plot to become humanity, and the appearance of the frickin' Time Lords – you'd better believe that there's enough backstage gossip and drama about The End of Time to fill several gigantic lists.
So, before RTD and Tennant make their triumphant returns for the 60th anniversary specials, let's look at the last time this magical duo was together.
20. The Regeneration That Never Was
The End of Time was the swansong for the much-loved Tenth Doctor.
After saving good old Wilf from a radiation booth, Ten embarks on a goodbye tour for the ages, before regenerating into Matt Smith's Eleventh Doctor in a blaze of glory. However, it could've been very different.
Russell T Davies originally wanted Ten's goodbye to be a subtle affair where the Doctor would die rescuing a seemingly unremarkable alien family. He liked the idea that the great Time Lord was so noble that he would sacrifice himself to save a group of ordinary people.
This was changed for two reasons: Davies was worried that such a simple story wouldn't play well over two hours, and that audiences would be disappointed to see a beloved character go out in such low-stakes circumstances.
He was probably right.