History NightmareFuel / HarryPotterAndThePrisonerOfAzkaban

** In a more realistic note, the fact the boggart during Lupin's Class takes the form of Snape for Neville. Meaning that Snape is so much of a SadisticTeacher he became a studient's worst fear.

** Want even more? In the book, Lupin states that if you suffer a Dementor's presence long enough, you may eventually become one. Sure, he may have been speaking metaphorically, but ''heavens''.
** It's established in later books that Dementors breed where there's lots of despair; [[FridgeHorror maybe they do it by]] [[WasOnceAMan turning people into more of them]]? Oh, and lest we forget, not only do they breed, but they're immortal and, by all appearances, un-killable.

* Boggarts. Creatures that can exist without any true form is pretty unnerving, but the fact that they can take the shape of [[YourWorstNightmare the thing a person fears most]], which can change on the person's mindset, and inhabit any given corner of the globe is pretty damn terrifying. The GiantSpider form of the Boggart in the movie is a good example. [[http://images.wikia.com/harrypotter/images/8/84/Spider.png See for]] [[http://images.wikia.com/harrypotter/images/5/5a/Spider2.png yourself]].

** In a more realistic note, the fact the boggart uring Lupin Class takes the form of Snape for Neville. Meaning that Snape is so much of a SadisticTeacher he became a studient's worst fear.

** The film adds extra creep factor to the scene in the Shrieking Shack: Accentuated by the music, Ron points to someone standing in the corner, the true form of the Grim, hiding behind the door that Harry and Hermione just walked through. In the dust covering the floor are paw prints, which the camera follows until it finds Sirius's shoes, then pans up to reveal that the {{hellhound}} that's been following Harry throughout the story is actually the mad murderer who they're all convinced is about to kill them: Sirius Black. The paw prints leading to a human being are downright unsettling; they create an unnatural sight, even by the standards of a wizarding school.
** Luckily, Sirius turns out to be innocent. But before that, he's a very unsettling character. Creator/GaryOldman's very unsettling performance doesn't help.

** Worse, that part where Pettigrew gives a mocking smile at the trio? He likely smiled at Harry Potter, knowing who he is, and eagerly awaiting Voldemort's return so he can give the dark lord info on the boy.

** Even worse, Lupin is a werewolf and Sirius has been in Azkaban for twelve years and can turn into a very large black dog. They both, given the forms they transform into, must know ''many'' gruesome ways of killing. Now... imagine if Harry ''hadn't'' interfered?

** Worse, that part where Walden gives a mocking smile at the trio? He likely smiled at Harry Potter, knowing who he is, and eagerly awaiting Voldemort's return so he can give the dark lord info on the boy.

** Every other creature in the Potterverse has some reference point in mythology (hippogriffs, trolls, etc). Dementors are one of Rowling's few original creations. The closest semblance they have to some are the Grim Reaper or Wraiths. Imagine you haven't read the books and you see that cloak and the creepy hand on the train for the first time. You'll quickly realize you're in whole new territory, going "What the hell is THAT thing?!!"

[[caption-width-right:350:[[YouDoNotWantToKnow You don't want to know what's behind that door.]] ''Unfortunately'', you're about to find out...]]

** When Parvati Patil is faced with a giant snake Boggart in the film, she responds by turning it into an infinitely ''more'' terrifying [[MonsterClown Jack-In-The-Box]] that bobs back and forth and, upon going forth, looks as though it's trying to ''grab'' you. Keep in mind, this was made from a spell that's essentially weaponized NightmareRetardant. How on Earth could she (or anyone, for that matter) regard this as funny!?

** Every other creature in the Potterverse has some reference point in mythology (hippogriffs, trolls, etc). Dementors are one of Rowling's few original creations. Imagine you haven't read the books and you see that cloak and the creepy hand on the train for the first time. You'll quickly realize you're in whole new territory, going "What the hell is THAT thing?!!"

** When Parvati Patil is faced with a giant snake Boggart in the film, she responds by turning it into an infinitely ''more'' terrifying [[MonsterClown Jack-In-The-Box]] that bobs back and forth and, upon going forth, looks as though it's trying to ''grab'' you. Keep in mind, this was made from a spell that's essentially weaponized NightmareRetardant. How on Earth could she regard this as funny!?

* So, back to those Dementors. The climactic scene where Sirius and Harry are at the lake under attack, there are ''swarms'' of them. The book makes it scary enough, but actually seeing it in the film, the part where one attacks Harry and you can ''see'' part of his soul getting sucked out, like some sort of double-consciousness, is horrifying, along with the screams of agony. Then two and three more attack, all sucking. And just what was that small bright light leaving Sirius's mouth? If the Dementors had swallowed it, his soul might have been lost forever.

* The lengths Draco Malfoy goes to get revenge for when he doesn't pay attention in Hagrid's class and gets injured as a result is to have [[ScrewTheRulesIHaveConnections his father convince a committee to kill Buckbeak]]. Imagine if some asshole got bit by your pet after refusing to listen to directions on how to handle it and he pulled strings to have it put down.

* The scene where Harry is in bed reading the Marauder's Map, and then suddenly he notices a name that really shouldn't be there: Peter Pettigrew. Now, as far as Harry knows, Pettigrew is a man who has been dead for 12 years. And yet here he sees him walking around Hogwarts on the map. When he goes to check, Pettigrew's name draws closer, but Harry can't see anyone in dark. Then, Pettigrew ends up right next to Harry, yet he still can't see anyone in the hallway with him. It ends up being NothingIsScarier on so many levels. Even on repeat viewings when you know what's really going on, (Peter is a rat that's scuttling around beneath Harry's view) it never really loses any of it's creep factor.

* The scene where Harry is in bed reading the Marauder's Map, and then suddenly he notices a name that really shouldn't be there: Peter Pettigrew. Now, as far as Harry knows, Pettigrew is a man who has been dead for 12 years. But yet here he sees his name walking around Hogwarts on the map. When he goes to check, Pettigrew's name draws closer and then ends up right next to him, yet Harry still can't see anyone. It ends up being NothingIsScarier on so many levels. Even on repeat viewings when you know what's going on, it never really loses any of the creep factor.

* The scene where Harry is in bed reading the Marauder's Map, and then suddenly he notices a name that really shouldn't be there: Peter Pettigrew. Now, from Harry's point of view, Pettigrew is a man who has been dead for 12 years. But yet here he sees his name walking around Hogwarts on the map. When he goes to check, Pettigrew's name draws closer and then ends up right next to him, yet Harry still can't see anyone. It ends up being NothingIsScarier on so many levels. Even on repeat viewings when you know what's going on, it never really loses any of the creep factor.

* The scene where Harry, Ron, and Hermione walk past Buckbeak's executioner. It's short but just the foreboding tone with the murder of crows gathered round the executioner as he sharpens his axe and the ominous track consisting of the ominous toll of bells, drums, and menacing horns plays. Worse is how Macnair watches as the kids pass and gives a [[SlasherSmile mocking, unsettling smile]].

* The scene where Harry is in bed reading the Marauder's Map, and then suddenly he notices a name that really shouldn't be there: Peter Pettigrew. Now, from Harry's point of view, Pettigrew is a man who has been dead for 12 years. But yet here he sees his name walking around Hogwarts on the map. When he goes to check, Pettigrew's name draws closer and then ends up right next to him, yet he still can't see anyone. It ends up being NothingIsScarier on so many levels. Even on repeat viewings when you know what's going on, it never really loses any of the creep factor.