As the 50th anniversary draws clower there have been many theories concerning the overall story. One of the biggest mysteries yet to be revealed is what exactly did John Hurt’s Doctor do that was so horrible that he lost his title of “The Doctor”. Well, lets look at a few hints from previous episodes and see what we can come up with.
In the episode The Beast Below, the 11th Doctor mentions that he would have to change his name after killing the star whale because he would no longer be a Doctor. So it’s probaby safe to assume that death was involved (genocide?). In the episode The Doctor’s Wife, the Doctor admits he was responsible for the destruction of the Time Lords. One possible theory is that The Doctor did in fact kill all of the Time Lords but at a specific point in time. The time was (maybe) after the end of the largest Time Lord victory during the war at The Gates of Elysium.
Here’s the theory: after the battle at The Gates of Elysium, Davros had fallen, the Daleks were driven off Gallifrey by the Time Lords, and they were all but victorious. However, this victory wasn’t enough for the now power hungry Time Lords. They wanted to erase every last Dalek out of existence. A new offensive was led by the Time Lords and a second Great Time War began. Knowing the Time Lords had to be stopped, the Doctor took it upon himself to end this Second Time War before it started. He tells the Time Lords that he is finished fighting and walks away from the war effort. He leaves the Time War and the Time Lords to start building “The Moment”
The Doctor returns some time later and uses “The Moment” to destroy all of the Time Lords (much like the Immortality Gate in ‘The End of Time’) and converts all of them into regeneration energy which is absorbed by The Doctor (John Hurt) giving him billions of regeneration opportunities. Then using the power of all the Time Lords, the Doctor “time locks” the events of the first Time War so that the war mongering will cease.
I believe that the crimes of John Hurt’s Doctor was the desctruction of a billion Time Lord lives. This does away with his regeneration limit and also explains why there aren’t any Time Lords left after the Time War except those left locked during war time. Its possible he put them in an infinite loop of fighting the same battles with the same outcomes, always ending on the day of their demise and beginning again on the day the Daleks first invaded. This is after all just a theory…