In folder example

Appearances

Dementors had a humanoid shape, approximately 4 metres, or 12 feet high, and were covered in long robes and hooded cloaks of ripped black cloth, making them closely resemble wraiths. Their skins were grey, slimy, and decayed-looking, like a decomposing corpse. Their breathing emitted a rattling sound, like it was trying to "suck more than air" out of a room. Their hands were "glistening, greyish, slimy-looking, and scabbed". They seemed to exude an aura of cold. When in a cluster, Dementors appeared as a foul mist.

A Dementor's mouth

A Dementor's face, which is usually completely hidden by their deep hoods, had empty eye sockets, covered with thin, scabbed skin. There was a gaping large hole where the mouth should've been, which was used for consuming the positive emotions of humans, as well as for sucking the soul out of the victim in a process called the Dementor's Kiss, leaving victims in a state generally considered worse than death. The Dementor pulled back its hood and sucked out its victim's soul, leaving the person an empty shell, alive but completely, irretrievably "gone". They were described as being able to glide over the ground only, and in any case, they couldn't pass through solid obstacles.[4]

Dementors were also known to be blind, as they did not have eyes. However, they could sense whether a presence was near them or not, by sensing the victim's emotions. This sense appeared to have been extremely acute, as the Dementors stationed at the entrances to Hogwarts Castle were able to sense the presence of Sirius Black walking beside the Great Lake in his human form. (It is interesting to note that many witches and wizards, including Hermione Granger, appeared to have had a misconception that Dementors were capable of vision, for instance, when Hermione proclaimed her certainty that the Dementors stationed at the entrances to Hogwarts would have seen Sirius fly into the school.)

Nature and behaviour

"He felt the unnatural cold begin to steal over the street. Light was sucked from the environment right up to the stars, which vanished... The cold was biting deeper and deeper into Harry's flesh... Then, around the corner, gliding noiselessly, came Dementors, ten or more of them, visible because they were of a denser darkness than their surroundings, with their black cloaks and their scabbed and rotting hands. Could they sense fear in the vicinity? Harry was sure of it: They seemed to be coming more quickly now, taking those dragging, rattling breaths he detested, tasting despair on the air, closing in —"
— Description of Dementors as they close in

Dementors seemed to suck all the light, sound, and happiness from the air as they drew long rattling breaths, and caused darkness to close in everywhere and the victim to feel incredibly cold. They could glide towards a victim with no sound other than then sounds of their own rattling sucking. However, this magically enforced darkness could be lit up by the Lumos Charm, as well as by the silver light of Patronuses.

Their sapience was heavily debated: they were sentient enough to taste and sense fear, being drawn to it and the promise of positive memories that it could feed off of. They were also intelligent enough to bargain: they obeyed the British Ministry of Magic for years because, in guarding Azkaban, they were provided with the sustenance of any remaining hope or happiness in the prisoners.

They could understand and follow at least simple instructions, which allowed Dementors to act as a bodyguard to Minister for Magic Cornelius Fudge in 1995,[7] to bury dead prisoners in the prison grounds, and to escort prisoners in and out of the Muggle-Born Registration Commission courtroom in 1997.[15] They could also communicate what they had heard Sirius Black saying in his sleep to the Ministry in 1993, and comment on his "less human, less complex" state of mind (in his Animagus form), implying that they could speak or otherwise communicate with wizards.

On the other hand, Albus Dumbledore described Dementors as savage creatures unable to differentiate between who they pursued and who stood in their way. He also informed the students to give Dementors no reason to harm them, saying that forgiveness and mercy were "not in the nature of a Dementor". And despite their having made bargains with humans - first with the Ministry of Magic, then with Voldemort - they seem to have had difficulty keeping these bargains in mind, as shown when, upon the Stunning of Umbridge by Harry, the Dementors in the room immediately abandoned restraint and attempted to kiss Mary Cattermole, apparently heedless of possible retaliations or repercussions from the wizards. Moreover, they had no soul of their own.

Outside of Azkaban, Dementors appeared to hunt for prey in groups of variable size, from as small as two to as large as greater than twenty. They appeared to attack by first surrounding their targets, cutting off any escape, then descending upon them all at once to feed. Ironically enough, however, in rare cases, Dementors have been shown forming a bond with a wizard and obeying their orders.

Abilities

They were genderless and did not mate, and they grew like fungus where there was decay. After Morfin Gaunt and Bartemius Crouch Jnr's mother died in Azkaban, Dementors buried their bodies, which showed that Dementors were capable of physical labour, such as grave-digging. Also, Sirius escaped when the Dementors came to give food, another sort of labour.

Muggles could not see Dementors, only wizards could.[23] It is unknown if other magical beings, like goblins and house-elves could see them. It was under debate if Squibs were able to see Dementors. While Arabella Figg had claimed in the Wizengamot court room to have seen the Dementors that had attacked Harry and Dudley in Little Whinging,[23] it was later confirmed that she had lied. It was unclear if she was unable to see the Dementors or if she was merely arriving late at the scene.[24]