Dementors
Background
Dementors are the guards of Azkaban. They can suck the spirit out of a person.
During the events of Harry Potter and the Prisoner of Azkaban (2004)
On the Hogwarts Train, Ron Weasley sees something moving outside and a group of Dementors come on board. One of them opens the door to the train car and starts to suck the joy from Harry Potter's spirit. Professor Lupin gets up and casts a spell, forcing the Dementor to retreat. During the Quidditch match, while Harry is chasing the snitch, he is attacked by Dementors and loses consciousness and begins to plummet to the ground. After he battles Lupin who has changed into a werewolf, Sirius Black crawls away and Harry finds him wounded near a lake. The air starts to get colder and a group of Dementors circle above. They start to attack Sirius and Harry casts the Patronus Charm and is then attacked by the Dementors. As Sirius' soul is about to be taken, a glowing stag appears and forces the Dementors to retreat.
During the events of Harry Potter and the Order of the Phoenix (2007)
Harry and Dudley Dursley run towards a walking underpass and are then attacked by Dementors. Harry casts Expecto Patronum and saves himself and Dudley.
