Jenny Greenteeth is a figure in English folklore. A river hag, similar to Peg Powler or a grindylow, she would pull children or the elderly into the water and drown them. She was often described as green-skinned, with long hair, and sharp teeth. She is called Jinny Greenteeth in Lancashire, but in Cheshire and Shropshire she is called Ginny Greenteeth, Jeannie Greenteeth, Wicked Jenny, or Peg o' Nell.
She is likely to have been an invention to frighten children from dangerous waters similar to the Slavic Rusalka, the Kappa in Japanese mythology, or Australia's Bunyip, but other folklorists have seen her as a memory of sacrificial practices. The demon may also lurk in the upper branches of trees at night.
A similar figure in Jamaican folklore is called the River Mumma (River Mother). She is said to live at the fountainhead of large rivers in Jamaica sitting on top of a rock, combing her long black hair with a gold comb. She usually appears at midday and she disappears if she observes anyone approaching. However, if an intruder sees her first and their eyes meet, terrible things will happen to the intruder.
The name is also used to describe pondweed or duckweed, which can form a continuous mat over the surface of a small body of water, making it misleading and potentially treacherous, especially to unwary children. With this meaning the name is common around Liverpool and southwest Lancashire.
In popular culture
Jenny Greenteeth inspired the lake monster (Meg Mucklebones) in the 1985 Ridley Scott fantasy film Legend. Jenny Green Teeth (note the words are separated) is the title character in a book of short stories, Jenny Green Teeth and Other Short Stories by New Zealand-born English writer and Scholar Joel Hayward. Jenny Green Teeth is also the main subject of a poem, "Welsh Maiden," by Joel Hayward in his collection, Lifeblood: A Book of Poems (2003).
In the novelette "Water Babies" by Simon Brown, Jenny Greenteeth is mentioned as being one of many names for a child-snatching water-demon. In the novella, an Australian police officer investigates a series of drownings that turn out to be predatory attacks by a seal-like creature.
She appears in Terry Pratchett's The Wee Free Men, attacking the main character Tiffany Aching and her brother Wentworth near a shallow stream.
Jenny Greenteeth appears in two Dungeons & Dragons (5th Edition) adventure modules: DDAL04-06 "The Ghost" (2016) , and DDAL04-14 "The Dark Lord" (2016) .
Jenny Greenteeth appears in the story "Something Borrowed" and in the novel Summer Knight, and is mentioned in the novel Proven Guilty, by Jim Butcher.