Most hags are schemers and plot-weavers. Annis hags are not. They spread terror through abject cruelty, gleeful appetites, and sheer physical power.
A hag known only as the Slicer lives in the moors of Leech Hollow. Once a season, she skins a man and leaves him in the village green of one of the nearby hamlets. She is known for wearing the skin of a manticore she killed with her bare hands, and she wears his iron teeth to complement her own in a set of braces that give her a second bite attack.
A hag coven needs a new maiden. The annis hag crone, Tessa Flint-Tooth, cannot abide the thought of another annis hag joining her company. Nor does she want Jenniver, the green hag mother, to gain a fellow green hag for an ally. They settle on a human, the future duchess of Kenmore, who secretly dabbles in witchcraft—and who is still a month away from her wedding day.
Though hags venerate both dark goddesses and witch patrons, they also have a progenitor mother: the original annis hag, Black Annis. Though not divine—at least, she does not answer prayers or grant spells—she is presumed alive and hale, still clad in the skins of all the children she has devoured over the years. She likely lives on either the Ethereal Plane or some demiplane (she almost certainly knows create greater demiplane (Ultimate Magic 213–214)). In terms of power, she is at least as strong as the famed Baba Yaga and has demonstrated both the aforementioned sorcerous abilities as well as witch powers from the Strength (Advanced Player’s Guide 70) and Vengeance (Ultimate Magic 83) themes. Approach with caution.
—Pathfinder Bonus Bestiary 11 & Bestiary 3 16
My middle school had a fair number of the Time Life Books’ Enchanted World series. I can’t recall which title had the description and image of Black Annis, but they were chilling.
In Classic Horrors Revisited, Rob McCreary has an excellent chapter on hags; of particular interest is how annis hags’ covens and powers differ from their sisters. He also deserves special props for nailing exactly why hags exist in the first place: men and women’s mutual fear of women outside the social order—by age, by accident, and by choice in particular.