[[quoteright:350:http://static.tvtropes.org/pmwiki/pub/images/robot_santa_8268.jpg]]
[[caption-width-right:350:{insert Jingle Bell Rock here}]]
->See, there's the thing. I'm the Doctor, but beyond that, I just don't know. I literally do not know who I am. It's all untested. Am I funny? Am I sarcastic? Sexy? Right old misery? Life and soul? Right-handed? Left-handed? A gambler? A fighter? A coward? A traitor, a liar, a nervous wreck? I mean, judging by the evidence, I've certainly got a gob.
-->--'''The Doctor'''

It's become traditional for a new Doctor's first serial to deal with regeneration trauma. The Tenth's is fairly mild -- compared to, say, [[Recap/DoctorWhoS21E7TheTwinDilemma the Sixth's brief homicidal mania]] -- and consists of him spending Christmas unconscious in bed. It's rather close to the Fifth Doctor's regeneration process, [[Recap/DoctorWhoS19E1Castrovalva where the Doctor spent a lot of time sleeping before running around a lot]].

The story is an interesting foreshadowing of what would become important themes in the next few series of ''Series/DoctorWho'' and its spin-offs: what happens when the Doctor ''isn't'' there to save the day.
----
Christmas Eve, and the TARDIS comes screaming down out of the sky into the Powell Estates. The new Doctor stumbles out of it and into the arms of Jackie and Mickey; he wishes them a happy Christmas before passing out in their arms. Understandably confused, they nevertheless help Rose carry him up to ''chez'' Jackie and get him settled in bed.

Mickey takes Rose out for a bit of last-minute Christmas shopping, where they are attacked by deadly robot Santas. Back at the flat, they are attacked by a deadly robot Christmas tree. The War On Christmas has never been so literal. The Doctor wakes up long enough to explain that the robot Santas aren't the threat -- they're just after the residual energy from his regeneration -- the ''real'' threat is the Sycorax warship that's just coming into view.

Meanwhile, about a third of humanity has zoned out and started climbing to the rooftops. This includes the royal family, but [[Recap/DoctorWhoS27E5WorldWarThree Harriet Jones]] (Prime Minister[[note]]Yes, [[RunningGag we know who she is]][[/note]]) encourages the British people not to panic. This doesn't exactly work, as the Sycorax leader pops up and demands that either the leaders of Humanity sell half of the species into slavery... or that third will leap off the rooftops. Rose and her companions have been paying attention to what's going on, thanks to Mickey's hacking skills, and they all slide into the TARDIS.

Unfortunately, without anyone realising it, the TARDIS is quickly stolen up into the Sycorax spaceship. Rose and Mickey exit the TARDIS in shock, finding themselves alongside a delegation from the Earth led by Harriet Jones (Prime Minister) trying to bargain with the Sycorax. Mickey spilled tea all over some of the TARDIS controls as he went out to see what Rose was screaming about, but it seems to be fine aside from some random smoke and sparks. Rose, realizing how utterly screwed over everyone is without the Doctor, tries to bluff her way out of the problem by using random phrases and words she's picked up from the Doctor. It doesn't work.

Luckily, however, Rose has bought enough time for the Doctor to finally finish off his regeneration cycle. As it turns out, the tea that Mickey dropped was just enough to jump-start the Doctor back into consciousness. Within a few seconds, the Doctor gleefully bounces around their ship, gives them a speech, realizes it's from ''Disney/TheLionKing'' and improvises a brief investigation instead, and decides that the Sycorax are simply bluffing -- that their blood control can't get people to kill themselves. All the while, he's running around and trying to figure out what kind of man this new body will make him. Manic and lucky, apparently. Within seconds, the Doctor challenges the Sycorax to a quick challenge for the fate of the Earth, to be decided in a sword-fight to the death. You know, the usual.

Luckily, the Doctor wins the fight in his jammies and dressing gown -- "very [[Franchise/TheHitchhikersGuideToTheGalaxy Arthur Dent]]" -- but not before losing a hand. Which he grows back, thanks to still being early in his regeneration cycle. The Doctor then demands that the Sycorax leave the Earth and tell any aliens who wish to conquer the planet that it is defended. Also, since no one can ''possibly'' deny alien life any more, Earth has now officially made first interstellar contact. Finally. And all ends well on Christmas Day...

...until Harriet Jones has them shot out of the sky by Series/{{Torchwood}} London. The Doctor, suddenly quite serious, decides to say a few simple words to begin the end her time as Prime Minister ("Don't you think she looks tired?" to her aide) and then he and Rose go off into the TARDIS and fly off all happily, though a bit troubled by the fact that the government of the UK is now crashing quickly and the "Christmas snow" is really ash from the Sycorax spaceship. Merry Christmas, everyone!

----
!!Tropes

* ArcWords: Harriet Jones calls '''Torchwood''' to take out the Sycorax warship.
* AstronomicZoom: The beginning there is this with the probe going to Mars.
* BackstabBackfire: After the Doctor wins their duel, the Sycorax leader gets up and charges him from behind. The Doctor (without looking or breaking his stride) throws the satsuma he's just found in his jim-jams at the hull switch, opening it under the Sycorax.
* BadassBoast: When someone wonders why Harriet Jones is speaking so casually about aliens as a matter of fact, she merely quips, "There's an act of Parliament banning my autobiography."
* BadSanta: A whole brass band of them, complete with [[InstrumentOfMurder weaponized instruments]].
* [[BigRedButton Big Red Threatening Button]]: That should never, ever, ''ever'' be touched. "I really don't know who I am. I don't know when to stop. So if I see a great big threatening button which should never, ever, ever be pressed, then I just want to do this.(He hits the button.)"
* BigShutUp:
-->'''Doctor''' I need...\\
'''Jackie:''' Is it food? Something simple? Bowl of soup? Nice bowl of soup? Soup and a sandwich? Bowl of soup and a nice ham sandwich?\\
'''Doctor:''' I ''need'' you to '''''shut up'''''!
* BondOneLiner: ''"No second chances. I'm that sort of a man."''
* CatchPhrase: Harriet Jones's has been accordingly upgraded to reflect her new status, which is met with some exasperation from everyone else -- since when did the Prime Minister need to introduce herself?
* ChristmasEpisode / AnAssKickingChristmas: It's Christmas in London and therefore supposed to be a 'day of peace'. Because the Sycorax don't respect this, The Doctor has to kick their ass. Then Harriet Jones blows their ship out of the sky.
* ClarkesThirdLaw: The Sycorax's blood control technology is described by one character as "like casting a spell".
* ContinuityNod:
** Rose's address to the Sycorax is basically her rattling off whatever useless bits of knowledge she's gained about aliens over the course of the last series.
** [[Recap/DoctorWhoS27E4AliensOfLondon Big Ben]] [[TheProducerThinksOfEverything is still covered in scaffolding]] from [[MonumentalDamage not being completely rebuilt.]]
** This isn't the first time [[Recap/DoctorWhoS19E1Castrovalva the Doctor's regeneration almost failed]]... or, for that matter, he spent a portion of the adventure sleeping.
** The Doctor's hand regrowth is also seen by some fans as an explanation of how Romana managed to do "trial" regenerations at the beginning of "[[{{Recap/DoctorWhoS17E1DestinyOfTheDaleks}} Destiny of the Daleks]]".
* ConvergingStreamWeapon: Used by Torchwood London against the fleeing Sycorax.
* {{Corpsing}}: It's not obvious due to camera angles, but Noel Clarke struggles to keep a straight face in the cold open.
* {{Eagleland}}: The United States immediately demands to take over the situation... not that Harriet cares.
* DisneyVillainDeath: The [[BigBad Sycorax Leader]] has a particularly nasty one here. Like in most [[DisneyAnimatedCanon Disney]] movies, you never see the body, but boy, that was a very LOOOOOOOOOONG fall there.
* EdibleAmmunition: The Doctor defeats the Sycorax leader with a satsuma.
* EpicFail: Rose's attempt to talk to the Sycorax using random words she picked up from the Doctor. The vast majority are just the names of previous [[MonsterOfTheWeek aliens of the week]], and the Sycorax just wind up laughing at her.
* EvilPlan: The Sycorax come to earth looking for slaves and minerals. They demand surrender so they can make another conquest.
* HesBack: "Did you miss me?"
* ImNotAngry: [[InvokedTrope Invoked]] by the Doctor in "The Christmas Invasion", against Prime Minister Harriet Jones.
-->'''Doctor:''' (''to an aide'') Don't you think she looks tired?
** This is a case of the Doctor deliberately manipulating the effect seen here: http://xkcd.com/799/
* InstrumentOfMurder: The robot Father Christmases wield brass instruments which double as weapons, including a trombone flamethrower and a tuba which, by dint of launching rockets, manages to make itself just barely more dangerous than the usual sort.
* LimbSensationFascination: When the Doctor's hand gets chopped off, shortly after his regeneration, there's a short focus on it as he grows a new one. "I've got just enough residual cellular energy -- to do this." (''regrows hand'') "...Wanna know the best bit? This new hand is a ''fightin''' hand."
* MassHypnosis: The Sycorax control of a third of the Earth's population.
* MoralDissonance: The Doctor deposes Harriet Jones, violating his own standards of not altering major historical events... and nobody ever, ever pulls him up on it. Not in this episode or anywhere else in the series.
* MythologyGag: The Fourth Doctor's outfit can be seen while the Doctor chooses his new clothes.
* NationsOfTheWorldMontage: we see people walking to the edge of buildings in Paris and Rome. With, of course, [[EiffelTowerEffect Eiffel Tower and Coliseum ]].
* NonSequiturThud: The Doctor on stepping out of the TARDIS in the intro. "Merry Christmas!" *thud*
* OminousFloatingSpaceship: The Sycorax ship.
* PajamaCladHero: After spending most of the episode laid up in bed, the Doctor does the climactic confrontation and duel still dressed in jimjams and dressing gown.
* PhraseCatcher:
-->'''Harriet Jones, Prime Minister:''' (''flashes ID badge'') Harriet Jones, Prime Minister.\\
'''Everyone (including the Sycorax):''' Yes, I/we know who you are.
* RationalizingTheOverkill: Harriet Jones justifies her blasting of the Sycorax spaceship out of the sky by saying that though the Doctor scared them off, they would show other, stronger, aliens the way to Earth. Given how frequently Britain had been invaded by aliens much mightier than these in the history of the series, past and future, the argument comes off as absolutely devoid of any weight.
** The point of this was also MakeAnExampleOfHim.
* RedShirt: Harriet Jones is beamed aboard the Sycorax ship -- along with three other people, for no particular reason. The only one that doesn't die notably has the role of acting as translator.
* ReplacementScrappy: In-universe, this is how Rose views the Tenth Doctor initially. She warms up to him later.
* ScrewDestiny: Harriet becomes the victim of the Doctor's decision to significantly alter her history after her first year as Prime Minister.
* ShoutOut
** After the defeat of the Sycorax leader, the Doctor mentions that he did "not bad for [[PajamaCladHero a man in his jimjams]]" and that this is "very [[Franchise/TheHitchhikersGuideToTheGalaxy Arthur Dent]]. Now that was a nice man."
** He also tries to convince the Sycorax that HumansAreSpecial by saying "Look at these people. These human beings. Consider their potential... [[Disney/TheLionKing from the day they arrive on the planet and blinking, step into the sun... there's more to see than can ever be seen, more to do than]] -- [[LampshadeHanging no, hold on. Sorry, that's the Lion King."]]
** Does that scene where the Doctor is hanging over the edge of the Sycorax spaceship, having had his hand cut off [[Franchise/StarWars remind you of anything?]]
** Evidently he still has ''Disney/TheLionKing'' on his mind when he has the defeated Sycorax champion hanging over the edge at sword-point -- "Leave this planet, and never return."
* SophisticatedAsHell: The Sycorax deliver an ultimatum demanding the Earth's every last resource, which is all fine and threatening until they end it with "[[BadassBoast Sycorax strong]], [[ProudWarriorRaceGuy Sycorax mighty]], [[RuleOfThree Sycorax]] [[TheLastOfTheseIsNotLikeTheOthers rock]]" (and no, this is not a BlindIdiotTranslation, as Harriet's assistant clarifies, "...as in the modern sense, they ''rock''.")
* SoundtrackDissonance: The Christmas tree attack is accompanied by a slightly deranged version of "Jingle Bells".
* SpotOfTea
** Tea is responsible for reviving the Doctor and ultimately saving the world. Did we mention that this show is British?
** In an earlier scene:
--> '''Mickey:''' [after Rose's mum insists they bring in a load of food into the TARDIS] We're having a picnic while the world comes to an end. Very British.
* Main/SuperPoweredRobotMeterMaids: Super-Powered Robot Santas; they have weaponry.
* SwordFight: Between the Doctor and the Sycorax champion.
* TakeThat: When the British PM is told that the President of the US has requested control of the FirstContact, she responds that he cannot be trusted not to start a war. [[UsefulNotes/GeorgeWBush In 2005...]]
* TitleDrop / RunningGag: Jackie uses the words "Doctor ''Who?''"
* WackyWaysideTribe: The Pilot Fish attack The Doctor, Rose, Jackie and Mickey early in the episode and are never heard from again after The Doctor destroys their Christmas Tree saw.
* WaxingLyrical: The Doctor starts accidentally quoting the lyrics of "Circle of Life" from ''Disney/TheLionKing'' when addressing the Sycorax leader.
* WhatTheHellHero: The Doctor was not very pleased when Harriet shot the retreating Sycorax ship. By UsefulNotes/TheLawsAndCustomsOfWar, he wasn't wrong, seeing as the Sycorax were retreating. Harriet defends herself with clause about them being "contingent to tactical necessity", and they can be waived from those who have shown themselves being willing to violate them such as when the leader tried to kill the doctor after swearing on his blood that he wouldn't.
--> "THAT WAS MURDER!"
* WritersCannotDoMath / ArtisticLicensePhysics: During the swordfight the Doctor's hand gets cut off. He can regenerate it, because he's still within the first fifteen hours of his regeneration cycle. Except that he arrived in London on Christmas Eve, while it was still light, and his hand gets cut off the next day, also during daylight hours. Christmas is only a few days after the winter solstice, and the night lasts longer than fifteen hours in London at that time.

----