5. "A Christmas Carol"
No one's denying that the 2010 Doctor Who Christmas Special is a great episode. But unlike those that came before, and better than those that follow, "A Christmas Carol" is a stand-alone festive episode like no other. In writing this special, Steven Moffat succeeds in revamping the well-worn Dickens holiday trope into a story worthy of the Doctor. "A Christmas Carol" is thoroughly enjoyable because it plays to every strength of both the show and Matt Smith's Doctor: the repercussions of changing the past through time travel, the stark contrast between the Doctor's carefree whimsy and manipulative brilliance, and the deeply emotional conflict that arises from moral dilemmas. This episode also gives us some of the Doctor's best lines: the hilarious quip "Finally, a lie too big" when his psychic paper cannot verify him as a mature and responsible adult; sighing that "Human beings. You always manage to find the boring alternative, don't you?"; and the oft-quoted "Do you know, in 900 years of time and space, I've never met anyone who wasn't important before." While there is undeniably a dark thread in the story's plotline, as a whole the episode is pure fun. What I like most about Matt Smith's Doctor is his childlike curiosity and the unadulterated joy he finds in the unusual. These qualities are foregrounded during Christmas, and delightfully enhanced with a compelling child companion. "A Christmas Carol" is a funny, suspenseful, and ultimately heartwarming episode - all the ingredients for an incredible Doctor Who Christmas special.