Harry Potter and the Prisoner of Azkaban director Alfonso Cuarón believes that the third movie is in fact a horror, as well as a noir.
Speaking with Total Film (thanks, GamesRadar), Cuarón said that when he read the book, there were two elements that stood out to him in particular. "There was the horror film element, but also the noir aspect of it," he said.
"In a way, when I was doing it, the model was more of the German cinema at the end of the silent era, and the transition into the talkies, like Fritz Lang to Murnau. You can see that some of Fritz Lang's films are kind of noir, but, at the same time, they have kind of horror elements to them. And, more importantly, particularly with Fritz Lang, through the genre, he was trying to convey - or just to project - the anxieties of his time. I think that what J.K. Rowling did with Potter, it was a reference of our times, of human behaviour."
We're not sure whether dementors were a key feature in the transition from the silent era to the talkies, but they certainly make the third Harry Potter film a bit spookier all-in-all.
Which Harry Potter film do you think is scariest?