The Machinist
A sickly insomniac, Trevor, is being tortured by a man named Ivan. The craziest part of this movie is that Ivan and Trevor are the same people and that Trevor created Ivan in his own imagination. Viewers were confused because Ivan was in scenes with other characters, but it turns out that he never actually interacted with anyone else.
The Babadook
The Babadook story revolves around a mother and son duo who are grieving the death of the patriarch of the household. At the end of the film, after they had apparently defeated the monster, the mother brings a bowl of worms downstairs to feed the monster. Some fans have discussed that the monster was just a manifestation and that fighting it didn't really mean anything, or that the monster never disappeared and she wasn't ready to let it go.