"The Next Doctor" is a special episode of the British science fiction television programme Doctor Who, broadcast on 25 December 2008 as the fourth Doctor Who Christmas special of the revived series. During its original airing, the episode had an audience of 13.1 million viewers and was the second-most-watched programme of Christmas Day 2008. It was the final Doctor Who episode to be filmed in standard definition.

David Tennant stars as the Tenth Doctor with one-off companions Jackson Lake (David Morrissey) and Rosita Farisi (Velile Tshabalala). The episode is set in London during the Christmas period of 1851. In the episode, the Doctor teams up with a man who appears to be another incarnation of himself; in their quest to foil a plot by the Cybermen to create a giant Cyberman called a CyberKing under the control of workhouse matron Miss Hartigan (Dervla Kirwan), the two inadvertently discover that the "new" Doctor is actually Jackson Lake, a regular human who began suffering from amnesia and believing himself to be the Doctor after interacting with Cyberman technology.