Doctor Who: 10 Times The Doctor Lost
1. When He Destroyed Gallifrey
While the outcome of the Time War was altered in 50th anniversary special The Day Of The Doctor, the guilt and pain that the Doctor felt as a result of that first, pre-Day Of The Doctor outcome cannot be erased.
In the episode, Doctors Ten and Eleven revisit the moment they chose to end the Time War by destroying the Daleks, the Time Lords, and Gallifrey itself, and manage to find a more peaceful solution, transporting the planet to a pocket universe instead of completely obliterating it. As things stand, "Gallifrey falls no more", but everyone from the War Doctor to the Thirteenth Doctor has memories of a time when it did fall, and they were the one who pulled the trigger.
Most of the time when we see or hear about Gallifrey on Doctor Who, we only hear about the Time Lords, the politics, the important men sat in the huge rooms making the big decisions. We often forget that the Doctor not only destroyed this part of his homeworld, but countless innocent civilians too. The number of casualties on his hands extends into the billions, and most of these people did absolutely nothing wrong, and were not involved in the war whatsoever.
The Doctor has more blood on his hands than any of the villains he comes face-to-face with each week, and the unspeakable act of horror the character committed during the final days of the Time War will forever be one of the most traumatic incidents in Doctor Who history.