Doctor Who: The Day of the Doctor is a special episode of the long-running British science fiction TV series Doctor Who, celebrating its 50th anniversary. It was broadcast on November 23, 2013, in both 2D and 3D formats. The episode features Matt Smith as the Eleventh Doctor, David Tennant as the Tenth Doctor, and John Hurt as an incarnation known as the War Doctor. It also stars Jenna Coleman as Clara Oswald and Billie Piper as Rose Tyler.
The plot revolves around the discovery of a forgotten incarnation of the Doctor, the War Doctor, who was forced to commit a terrible act in order to end the Time War between the Time Lords and the Daleks. On the verge of activating a weapon of mass destruction to destroy both sides, the War Doctor meets his future selves, the Tenth and Eleventh Doctor, who have been brought to his time by a mysterious force. Together, they must find a way to stop the destruction of Gallifrey, which they thought they had destroyed in the Time War.
The Day of the Doctor also features appearances by several classic Doctor Who characters, including Tom Baker, the Fourth Doctor, who appears in a cameo role as the “Curator” of the National Gallery, and the Zygons, a shape-shifting race of aliens who made their first appearance in the 1975 serial Terror of the Zygons.
The special episode was written by showrunner Steven Moffat and directed by Nick Hurran. It was well-received by fans and critics alike, with many praising its inventiveness and its celebration of the series' rich history.