The 10 best modern 'Doctor Who' episodes
Pompeii, Christmas, Fireplaces and more
7. 'Christmas Invasion'
Why we love it: Not only was this the first true Christmas special of the series, it introduced both David Tennant and Torchwood. Still, the episode might be almost as notable for its handling of Prime Minister Harriet Jones. When she orders Torchwood to shoot down the retreating enemy, the Sycorax, the Doctor is furious and tells her he can bring her down with just six little words. After he whispers, "Don't you think she looks tired?" to one of her aides, she's soon fending off rumors about her health and facing a vote of no confidence. It's a clever piece of writing that more than makes up for the silliness of killer Santas. In the end, though, the kudos really go to Tennant. In making his debut, he established himself as a warmer and wittier Doctor that even devoted Eccleston fans grew to appreciate.
-Liane Bonin Starr