Prequel

The Prequels were a series of prologues to certain episodes of Doctor Who from Series 6 and 7. They were released by the BBC on their official site. They were similar to the Tardisodes produced for Series 2.

Series 6

 * The prequel to The Impossible Astronaut
 * The prequel to The Curse of the Black Spot
 * The prequel to A Good Man Goes to War
 * The prequel to Let's Kill Hitler
 * The prequel to The Wedding of River Song

Series 7

 * The prequel to The Doctor, the Widow and the Wardrobe
 * The prequel to Asylum of the Daleks
 * The Making of the Gunslinger a prequel to A Town Called Mercy
 * The Snowmen also had two different prequels. The first, The Great Detective, was given a television broadcast as part of the 2012 Children in Need event. The second prequel was released online the following month.
 * The prequel to The Bells of Saint John

Home video release

 * The Prequels for The Impossible Astronaut, The Curse of the Black Spot, A Good Man Goes to War, Let's Kill Hitler and The Wedding of River Song were released on the Complete Series 6 DVD and Blu-ray box set in November 2011.
 * The Prequel for The Doctor, the Widow and the Wardrobe was released on the DVD of the story in January 2012.
 * The Prequels for Asylum of the Daleks and A Town Called Mercy were released on the Series 7: Part 1 DVD in October 2012.