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. Another prequel was released in the build-up to this episode, though it detailed the events which took place just after A Good Man Goes to War and did not directly relate to events or characters from The Bells of Saint John, acting more as another prequel to The Snowmen.

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.