Doctor Who: 10 Times The Doctor Lost

Series 10's Oxygen tackles corporate greed and capitalism. In the episode, the Doctor and his gang use spacesuits that have a limited air supply, a policy enforced by the company who manufactured said suits. In this world, oxygen is a precious resource, and the company wants to use as little as possible, even going so far as to consider the suit-wearer expendable if they breathe too much air. Bit mean that.

To counter this system, the Doctor attempts to take his group to a location where they would be "offline", and thus undetectable by the company. Sounds simple, right? Well, unfortunately, things don't go as smoothly as that.

Along the way, the Doctor is forced to give Bill his helmet, which saves her life, but leaves the Time Lord blind. Like, fully, properly blind. When this happens, your first thought will be that he'll be cured by the end of the episode, but he actually stays this way for the next couple of adventures, and his sight is only restored in exchange for a group of sinister Monks seizing control of the Earth. Because when you're the Doctor, the hits just keep on coming.

While the Doctor's blindness wasn't used as well as it could have been (it comes across as a minor inconvenience rather than a life-changing disability), it forced him to approach the whole "save the universe" game from a different angle, and it was actually refreshing to see the events of Oxygen have lasting consequences, rather than being tied off in that initial 45-minute episode.