What is a hag in Harry Potter?

Question

In the Harry Potter books, there are a number of mentions of "hags":

"They say [Quirrell] met vampires in the black forest, and there was a nasty bit o' trouble with a hag."
_{Hagrid, The Philosopher's Stone Chapter 5: Diagon Alley}

Second year students will require:

The Standard Book of Spells, Grade 2 by Miranda Goshawk
Break with a Banshee by Gilderoy Lockhart
Gadding with Ghouls by Gilderoy Lockhart
Holidays with Hags by Gilderoy Lockhart
_{The Chamber of Secrets Chapter 4: At Flourish and Blotts}

Harry ate breakfast each morning in the Leaky Cauldron, where he liked watching other the guests: funny little witches from the country, up for a day's shopping; venerable looking wizards arguing over the latest article in Transfiguration Today; wild looking warlocks; raucous dwarfs; and once, what looked suspiciously like a hag, who ordered a plate of raw liver from behind a thick woollen balaclava.
_{The Prisoner of Azkaban Chapter 4: The Leaky Cauldron}

What exactly is a hag, though? I have yet to find any sort of description, and can only guess that they are rather unpleasant creatures. I'm hoping for something canon-based.

Answer 1

While there's no official Potterverse description of a hag in Fantastic Beasts and Where to Find Them, in Chamber of Secrets, Harry describes Millicent Bullstrode of Slytherin as looking like a hag he saw a picture of in Gilderoy Lockhart's book Holidays with Hags. Presumably, a hag can be female, large in stature, with a square-shaped body, and sporting a heavy, jutting jaw. A female hag may be larger than a male human. Note: I don't know if in Chamber of Secrets Harry was still a bit small and skinny for his age, so take my last statement with a grain of salt.

Malfoy strutted over, smirking. Behind him walked a Slytherin girl who reminded Harry of a picture he’d seen in Holidays with Hags. She was large and square and her heavy jaw jutted aggressively. Hermione gave her a weak smile which she did not return.
_{Chamber of Secrets - page 143 - Bloomsbury - chapter 11, The Duelling Club}<

AND

Hermione and Millicent Bulstrode were still moving; Millicent had Hermione in a headlock and Hermione was whimpering in pain. Both their wands lay forgotten on the floor. Harry leapt forward and pulled Millicent off. It was difficult; she was a lot bigger than he was
_{Chamber of Secrets - page 144 - Bloomsbury - chapter 11, The Duelling Club}

In Prisoner of Azkaban, Harry encounters what he believes to be a hag having a breakfast of raw liver in the Leaky Cauldron. If this is indeed a hag it would seem that hags in Potterverse do assimilate into wizarding society, at least enough to appear in public at the Leaky Cauldron and eat raw liver.

Harry ate breakfast each morning in the Leaky Cauldron, where he liked watching the other guests: once, what looked suspiciously like a hag, who ordered a plate of raw liver from behind a thick woollen balaclava.
_{Prisoner of Azkaban - page 42 - Bloomsbury - chapter 4, The Leaky Cauldron}

Apparently Hogsmeade is enticing to magical beings, it being the only fully magical town in Britain. Harry thinks he sees another hag in the Three Broomsticks and notes that hags are not as adept as disguising themselves as wizards are.

The Three Broomsticks was packed, mainly with Hogwarts students enjoying their free afternoon, but also with a variety of magical people Harry rarely saw anywhere else. Harry supposed that as Hogsmeade was the only all-wizard village in Britain, it was a bit of a haven for creatures like hags, who were not as adept as wizards at disguising themselves.
_{Goblet of Fire - page 280 - Bloomsbury - chapter 19, The Hungarian Horntail}

If I find additional information on the hag, I will edit it into this answer.

ETA: Yes, I realize that it says Millicent reminded Harry of 'a picture he saw in Holiday with Hags' and does not specifically say 'a picture he saw of a hag in Holiday with Hags'. However, as the book is titled Holiday with Hags, I don't think it's much of a stretch to imagine the picture Harry referred to seeing in the book was quite likely a hag.

Answer 2

The hag is a child-eating creature of human appearance, though likely to have more warts than the average witch.

The most clear description of Hags comes from a short excerpt of The Dark Forces: A Guide to Self-Protection, that Rowling wrote for the old Pottermore.

Werewolf bites should be thoroughly and magically cleaned, as the werewolf’s fangs are venomous. However, there is no cure once you have become a werewolf, so try and avoid being bitten at all costs.

Avoid the Red Cap, a Dark dwarfish creature that lurks in places where blood has been shed and will attempt to bludgeon the unwary to death.

The Zombie dwells only in the Southern part of America. It is an example, like the Vampire, of the Living Dead and may be recognised by its greyish colour and its rotten smell.

The hag is a child-eating creature of human appearance, though likely to have more warts than the average witch.

_{Pottermore (old version) - The Dark Forces: A Guide to Self-Protection}

While hags do not appear much in the main books, they appeared in some of Rowling's other Harry Potter writings.

The first issue of the Daily Prophet newsletter contained a letter to the editor from a Hag ("A Word in Support of Hags") giving a not-too-convincing account of how peaceful hags are.

The last issue contained a short article ("New Potion gives Hope for Hags") about a potion that would reduce a Hag's desire for human flesh.

Information from the 2nd and 3rd W.O.M.B.A.T. tests show that, "Hags eat small children" and "have four toes on each foot", but "have only rudimentary magic, similar to that observed in trolls." The Ministry is said to consider Hags to be "less dangerous" than Werewolves and Inferi.

The Famous Wizard Cards talk about a "Society for the Reformation of Hags" founded in the seventeenth century, and the Prisoner of Azkaban video game contains five collectible Hag cards (though the PoA cards were never confirmed to be written by Rowling.)

Answer 3

Since Rowling doesn't further describe Hags, I presume she assumes most of us are already familiar with lore about them. She draws many of her creatures from already existing lore such as Garden gnomes, boggarts (though she dramatically changes what they are - hers are way cooler than the traditional boggart) goblins, the hippogriff, basilisks,and the hag to name only a few.

Around the world there are stories of malevolent creatures that take on the appearance of an old, bent women. She is often linked with nightmares. In fact, in Medieval lore when one awoke short of breath it was believed that person had been "hag-ridden" where the hag sat on the victim's chest while he or she slept. In Norse legend she is called a Mara or Mare (Nightmare) and in Polish mythology a Nocnitsa. In Scotland she is called the Cailleach and is associated with the destructive forces of nature instead of nightmares, plus she is described as being huge instead of human-sized. Baba Yaga (although sometimes this Russian Hag is also helpful), and Bahktak are also examples of Hags. Another example of a hag many of us familiar with Grimms Fairy Tales is the "witch" in Hansel and Gretel. Some traditions hold that she specifically preys on children. You can generally think of them as the female version of the "boogy man." and wild witches of the wilderness.

Apparently "Hag" comes from an old English word that can be translated as witch, but as Rowling seems to be making a differentiation between the two, I'd say she is depicting the forest dwelling, wild, ugly and somewhat more malevolent witch.

http://www.thefreedictionary.com/Hags

http://www.wordorigins.org/index.php/hag/