Doctor Who: 10 Worst Things The Twelfth Doctor Ever Did
2. Abandoning Clara, Courtney And Lundvik In Kill The Moon
The infamous Kill The Moon; there are few episodes that have such a negative reputation as this and for good reason. Not only does it engage with some of the loosest science fiction the show has ever done - which is saying something for Doctor Who - but it includes one of the most callous acts the Doctor has committed.
In this episode it's revealed that apparently the Moon is a giant egg and the characters are forced to make the choice whether to let it hatch and risk the lives of everyone on Earth or kill the baby and save the Earth. Either option isn't ideal and someone with the knowledge and wisdom of the Doctor should be a major asset. So what does the Doctor do? Leave.
While the Doctor later justifies this by saying he can't make decisions that big for humanity and they had to make choice for themselves, it's hard to argue he did the right thing by just abandoning the situation.
To make matters worse, one of the people he leaves to make that choice is Courtney Woods, who's only a teenager and thanks to the Doctor she gets left in an incredibly tense and dangerous situation.