3. Execution
The Doctor is not known for vengeance though it has happened in the past he sent Solomon from Dinosaurs on a Spaceship to his death without much or really any soul searching. There arent many irredeemable characters in Doctor Who but Solomon, who wiped out the Silurian race, was definitely one of them. Another is Mrs. Gillyflower from Crimson Horror, who killed a number of people and tortured her daughter. The Doctor is only indirectly involved in Mrs. Gillyflowers death but he makes it clear he does not mourn her. And he certainly doesnt chastise Ada when she kills the parasite. On the other hand, he has great sympathy for the Ice Warrior in Cold War who is hell-bent on launching the subs nuclear missiles and causing the destruction of the earth. The Doctor respects Skaldak as a creature of honor, recognizing him as another soldier who has lost his people. Clara talks Skaldak out of his need for vengeance by reminding him of his love and pride for his own family. The Doctor is not above using death and destruction as a way to combat a greater evil. While we do not often see him in the role of executioner, it is an established part of his persona. This leaves one to wonder what exactly did the John Hurt Doctor do that was so above and beyond the dark side we have already witnessed that his other incarnations have disavowed him?