10 Doctor Who Episodes Where Evil Won
3. The Doctor Falls
The situation in The Doctor Falls is truly hopeless. The Cybermen are relentlessly converting the colony ship's residents, Bill has been turned into a Cyberman, the Master and Missy are content to make things worse or bugger off entirely, and there's seemingly no way off the ship. And yet, the Twelfth Doctor continues to make a stand, as he explains to the Master and Missy in his impassioned speech:
"If I run away today, good people will die. If I stand and fight, some of them might live. Maybe not many, maybe not for long."
The Doctor succeeds in buying Nardole, Alit and the kids time to escape to the upper floors by destroying as many Cybermen as he can. However, he's eventually gunned down by the Cybermen, left for dead on the scorched earth of a battlefield. It's a heroic sacrifice, but it can't be called a victory.
As Nardole later observes, the Cybermen will eventually regroup, and then it will be up to him and Alit to come up with some other solution to repel them. It's a bleak reminder of how relentless the Cybermen can be, and how it's highly likely that they'll eventually win in the end.