- "We actually prefer justice demon. FYI"
Vengeance demons, or justice demons as they preferred to call themselves, were an all-female species of demons who had the power of granting wishes of vengeful intent. Their ranks were gathered by D'Hoffryn, who sought out women who exacted curses on those who have done them harm. They were female immortal beings who traveled the world exacting vengeance on behalf of their victims such as wronged women, scorned men, dying people, and even neglected or abused children.
Vengeance demons appeared as humanoid demons with the appearance of heavily wrinkled or decaying skin. They could choose to appear in their true forms to intimidate their victims, or they could modify their appearance to that of a normal human to facilitate interaction with their target clients. According to D'Hoffryn, vengeance demons retain a soul, although whether their souls were similar to human souls or different altogether was never mentioned. 
Vengeance demons traveled the world exacting vengeance on behalf of victims. Their typical method was to appear to a wronged person, in human form, and encourage them to vent their frustration about those who have hurt them. The moment the object of the demon's attention expresses their preferred method of punishment in the form of a wish, the vengeance demon could cause his or her wish to come true, whether it required gruesome dismemberment or even the creation of a new alternate universe. Although vengeance demons' mission in as a whole was to bring forth "destruction and chaos for the pleasure of the Lower Beings", each individual had her own priorities and specialties, such as scorned women or neglected children. Some vengeance demons did not believe their mission was evil at all, and described themselves instead as "Justice Demons," a term which carries less stigma than "Vengeance Demons".
In a manner, vengeance demons were somewhat similar to the classic depictions of genies, as they'd obey the exact wording of the wish, but do not give the wish-maker what they wanted. For example, when Cordelia Chase wished to Anyanka that Buffy Summers had never come to Sunnydale, Anyanka instead altered history so that the Order of Aurelius ruled Sunnydale with an iron fist, as Buffy was not there to oppose them. Similarly, when Dawn Summers wished to Halfrek that no one would leave her, it instead resulted in anyone and everyone who entered the Summers' residence being mystically trapped inside the house and unable to leave the premises.
- "You have much anger and pain. Your magic is strong, but your pain... it's like a scream that pierces dimensional walls. We heard your call."
D'Hoffryn created vengeance demons by appearing to humans who have exacted notable revenge on their loved ones, and transforming them into demons. These humans are generally females, and D'Hoffryn typically chooses those who already have decent magical aptitude, as they generally make the best Vengeance Demons. He created Anyanka, Patron Saint Of Scorned Women by this process, but failed to convert Willow Rosenberg. The recruitment process was a polite one, and the women have the option of declining the offer. When this occurred, D'Hoffryn granted them a talisman which they could use to summon him, should they change their mind at a later date.
- "The flaying of Warren Mears? Oh, truly inspired. That was water cooler vengeance. Lloyd has a sketch of it on his wall."
Despite the severity of the vengeance they inflict, vengeance demons were humorously implied to be the white-collar workers of the demon world. Throwaway comments by Anya, Halfrek, D'Hoffryn all suggest an office-like setting, where demons relate their stories of vengeance and gossip to each other.
There were rules that governed the Vengeance demons and the wishes they granted and on the terms of their performance. When Anya took back a wish she granted, she is punished by having to file a flight plan whenever she wished to teleport. When Anya wished to reverse her actions that resulted to the death of a dozen fratmen, D'Hoffryn reiterated that such a reversal would require the life and soul of a vengeance demon to appease the Fates. Such wish of Anyanka caused her to be removed by D'Hoffryn from the ranks of his vengeance demons, as Anyanka has shown weakness and reluctance to continue her mission for vengeance. D'Hoffryn was also most vengeful upon his perception of Anya's weakness, and not only denied Anya the easy death she asked for, he also specifically chose her best friend Halfrek to die instead to reverse Anya's work.  D'Hoffryn also later sent a demon to assassinate Anya. 
Powers and abilities
- "Wish granted."
Vengeance demons had the ability to grant wishes of vengeance; this power was derived from the amulets they wore around their necks. However, they cannot grant their own wishes or those of another Vengeance Demon. The resulting effects of the wishes they grant are quite powerful (able to create alternate timelines, if necessary, as precisely what happened when Cordelia made a wish to Anya), since Anya claimed that only the Vengeance Demon responsible for granting the wish can undo it; and if the wish happens to have been stated specifically enough, even Vengeance Demons are not exempt from the effects of the wish once granted, as seen when Halfrek failed to teleport away after entering a house affected by a wish (that she herself granted) that prevents people inside from leaving it. Apart from that, if their amulet was destroyed, their wishes could be undone and they became mortal again. They could sense when people had vengeful feelings in their souls, and can identify whether creatures have souls or not by simple contact, or merely by observing them at close range; this is very useful when distinguishing normal people from soulless beings, like Vampires. Vengeance Demons also appeared to have the ability to summon their amulets, as Anyanka was seen wearing her amulet moments after being summoned by Giles, who had it up until that point. This would explain why Anya was not concerned with losing her power centre when giving it to Cordelia Chase.
Vengeance Demons could transform into a frightening demonic form from human form, in which their faces appeared to be skinless with exposed veins.
Vengeance Demons could live for thousands of years and remain ageless.
Vengeance Demons could resist a degree of damage without being harmed by it, at least to extent that both Halfrek and Anya have both been struck with a sword to the chest and survive, removing the sword with pain but recovering easily to continue fighting.
Superhuman StrengthAs a Vengeance Demon, Anya was able to knock opponents several meters away as well as battle powerful beings such as the Slayer and possess enough strength and endurance to rival the Slayer's.
One Vegeance demon, Halfrek, has at least once shown the ability of telekinesis by by pushing a human Anya away pointing her arm at her.
Both Halfrek and Anyanka have once appeared to have altered their voice to make them sound more threatening.
Vengeance Demons have shown to have possessed some empathic abilities. This was mainly used for soughting out their wronged person, feeling their pain as if it was their own. Anya felt Willow's pain after losing Tara Maclay and used this to track her down. Anya could also sense that Spike had gained a soul via simple contact.
Mind Control Immunity
Anya has also claimed that they are immune to the form of mind control which was manipulated by wicthes such as a corrupted Willow Rosenberg by telepathically communicating with the mind, yet this was done when she forced Anya to free her from Giles' binding spell.
Notable vengeance demons
- Anyanka — specialized in granting the wishes of wronged or scorned women.
- Halfrek — specialized in granting the wishes of neglected or abused children.
- Malice — specialized in granting people their dying wish.
- D'Hoffryn — the employer/master of all The Vengeance Demons.
- "The Wish" (1st Appearance)
- "Pangs" (First identified)
- "Doublemeat Palace"
- "Older and Far Away"
- "Hell's Bells"
- "Seeing Red"
- "Two to Go"
- "Beneath You"
- "Same Time, Same Place"
- Go Ask Malice