5. The End Of Time
The only two-parter on this list, and I'm not cheating because New Year's Day (on which Part 2 aired) is still part of the festive season. The End of Time, being a regeneration story, came with higher audience expectations than the usual Christmas special and as such has severely divided fandom, but looking back it's a rather fitting end for the 10th Doctor. What's bad about it? Well, the Master turning everyone on Earth into himself is a little farfetched, even by RTD standards, but that was largely there for the cliffhanger and was quickly done away with, so we can forgive that. The Vinvocci (don't call them cactuses - or even cacti) are slightly annoying and the Doctor's regenerative farewell tour goes on a bit longer than necessary. But that's really it. Bernard Cribbins' Wilfred - not-so-surprise hit of series 4 - is promoted to companion, and his dialogue with the Doctor is tremendous throughout (his response to setting foot inside an alien spaceship for the first time, aka fulfilling his lifelong dream? "I thought it'd be cleaner." Priceless). David Tennant is also on stellar form in his last adventure, gloomily anticipating his demise in quieter moments and rising to the challenge in usual 10th Doctor style when the stakes are raised. Timothy Dalton is a chilling Time Lord president (and Rassilon at that! How's that for fan service?) and John Simm plays the Master with none of the smug, smarmy, hand-clapping melodrama he displayed the first time around. Last of the Time Lords is a distant memory. Christmas is merely a backdrop for this story, and it's not really regarded as a Christmas Special so much as a series finale (as I'm sure The Time of the Doctor will also be, given its nature), but it's a great story nonetheless - epic and heartbreaking in equal measure.