10. The Christmas Invasion
The first adventure to feature David Tennant (not including his appearance in The Parting of the Ways) was also the first Christmas special of the new era. Focusing on the post-regenerative crisis which the Doctor undergoes, and a threat from the stars which is eventually revealed to be the Sycorax (who intercept a Mars-bound satellite), it is sometimes viewed as the best Christmas special out of the eight which have been made so far. The episode is particularly memorable for the performance of Tennant, who sets out to make the character his own, and begins the mystery of Torchwood, who would prove to be a major player in the second series. He displays humor and charm when dealing with Rose and Jackie, particularly confused when dealing with oranges in the pockets of his dressing gown which is used to surprisingly good effect later in the episode. The anger and ruthlessness he shows when dealing with the Sycorax, which was perhaps present in Chris Eccleston's character but never realised, is also on show. Not only this, but the episode is very humorous in general, from the Santa assassins to the spinning Christmas tree, it is a Christmas episode, but at the same time, is also obviously Doctor Who, providing the perfect platform for Tennant to begin shaping the character.