The Harry Potter universe is filled with dangerous and mysterious creatures that offer a range of terrifying abilities. Werewolves like Remus Lupin are a great example because even though he's in control as a human, his disease makes him unpredictable. There are also Acromantulas, which are massive spider-like creatures that offer no safety to humans. But the one creature that has posed the greatest threat to the Wizarding World has been the Dementors. In fact, these creatures were so dangerous that they required a spell, Expecto Patronum, to keep them at bay.
Source：https://www.cbr.com/harry-potter-theory-dementors-innocent-people-azkaban/
