Dementors

Dementors are horrible, spectral magical creatures, hooded and robed, which feed on positive human emotions and leave only the negative ones.

Dementors drain ‘peace, hope, and happiness out of the air around them,’ according to Professor Lupin (PA10). Even before a Dementor is seen, its presence is obvious; they are surrounded by an unnatural darkness and terrible icy cold (PA5).

Dementors affect even Muggles, although the Muggles can’t see the foul, black creatures (OP1, OP8). They were the guards at Azkaban prison and made that place horrible indeed. The Ministry of Magic used Dementors as guards in its courtrooms as well (GF30, DH13). When they breed, they create chill mist which permeates everything (HBP1). They drain a wizard of his powers if left with them too long. A Dementor’s breath sounds rattling and like it’s trying to suck more than air out of a room. Its hands are “glistening, grayish, slimy-looking, and scabbed”. It seems to exude cold (PA5).

A Dementor’s last and worst weapon is called the Dementor’s Kiss. The Dementor puts back its hood and clamps its jaws on the mouth of the victim and sucks out his soul, leaving him an empty shell, alive but completely, irretrievably “gone” (PA12, PA20).

There are certain counter-measures one can use against Dementors, specifically the Patronus Charm (PA12, PA20, PA21, OP1, OP27, MagSp).

Dementors come onto the Hogwarts Express (PA5)

“They sort of freeze your insides, don’t they?”
— Fred Weasley (PA6)

Dementors attend a Quidditch match (PA9)

The description of Dementors by Professor Lupin (PA10)

Descriptions of the Dementor’s Kiss (PA12, PA20, GF36)

Dementors can be defeated by Patronus Charm (PA5, PA12, PA20, MagSp)

“sightless, soul-sucking fiends” (GF2)

Albus Dumbledore’s opinion of them (PA4)

Dementors feed on positive emotions, leaving only the negative ones (PA10)

Dementors have pale hands, dead-looking (PA5)

A Dementor gave the Kiss to Death Eater Barty Crouch Jr. (GF36)

Dementors attack Harry and Dudley in Little Whinging (OP1)

Petunia Dursley had heard “that awful boy” – meaning Severus Snape – tell her sister Lily about Dementors at Azkaban (OP2, DH33).

Mrs. Figg could both see and feel the coldness of the Dementors even though she was a Squib (OP8)

Dolores Umbridge sent the Dementors to attack Harry (OP32)

Dementors left Azkaban when Lord Voldemort took over, causing a depressing mist everywhere (HBP1)

Professor Snape disagreed with Harry about the best way to defend against a Dementor, but Snape’s method is unknown. Possibly he wanted Harry to use something less showy than a Patronus (HBP21)

Harry thought the Dementors had changed Dudley’s personality for the better (DH3)

Umbridge had Dementors guarding the Muggle-borns at the Ministry, while she protected the judges with her silver cat Patronus. Harry was undercover and couldn’t use his Patronus, so he thought about helping Ron and Hermione as a happy thought to hold back fear and depression. Eventually he had to use “Expecto Patronum” to save Mrs. Cattermole and the others (DH13)

Some Death Eaters wanted to let Dementors “kiss” Harry to weaken him for the Dark Lord, but Harry fought them off with his Patronus (DH28)

Dementors fought for Voldemort during the Battle of Hogwarts (DH32)

When surrounded by his loved ones, thanks to the Resurrection Stone, Harry felt no chill from the Dementors (DH34).