Black Annis, also known as Black Agnes, was a formidable witch in English folklore. She is said to have a rather terrifying blue face and glowing eyes. Rather than conforming to traditional dietary habits, Black Annis chose to feast upon the flesh of humans, specifically children. According to English legend, she prowls the countryside around Leicestershire, looking for her next unwary victim.
As mentioned in The Alchemyst, Black Annis is a vile, dark creature of the night and even thinking about her could cause madness. When Nicholas Flamel and Scathach are contemplating an Elder that could awaken Josh Newman, they consider Black Annis, along with Persephone. Both however, were deemed insane and too dangerous to make contact with. Black Annis is said to be residing in the Catskills and according to Scatty, if her grandmother, The Witch of Endor (also known as Zephaniah), knew where Black Annis was, she would not let her live.