Seven deaths of Davros

The seven deaths of Davros were witnessed by the War Doctor during the Last Great Time War. (PROSE: The Day of the Doctor) Davros was the creator of the Dalek race and, during the first year of the Time War, was believed dead when his command ship was destroyed by the Nightmare Child. (TV: The Stolen Earth) The War Doctor did indeed witness this event. (PROSE: The Third Wise Man)

Behind the scenes
The seven deaths of Davros share their name with the time travel murder mystery novel, which was released a few months before The Day of the Doctor.