Over Doctor Who's long history, what prompted the decision to leave for those in the lead role of the Time Lord known as The Doctor.
With the 13th Doctor recently announced (expect a video on that soon!) and the 12th Doctor's time in the TARDIS coming to an end I look back through the history of the show to investigate why the actors have left one of the most sought after acting jobs in television.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------


Sources-
The Doctor His life and Times - BBC

Den of the Geek-
http://www.denofgeek.com/uk/tv/doctor-who/49168/doctor-who-the-behind-the-scenes-causes-of-regeneration