Jenny Greenteeth is a river-hag of English folklore who pulls children or the elderly into the water and drowns them. She is described as green-skinned, with long hair and sharp teeth. She is Jinny Greenteeth in Lancashire and north Staffordshire, and Wicked Jenny, Ginny or Jeannie Greenteeth in Cheshire and Shropshire; the name is thought to derive from “Grinteeth,” an alternate name for the grindylow.
The same name is used for pondweed or duckweed, which can form a continuous mat over a small body of water and make it misleading and treacherous, especially to unwary children; with this meaning it is common around Liverpool and southwest Lancashire. She is likely an invention to keep children away from dangerous water, like the Slavic rusalka or the Japanese kappa, though some folklorists believe the tale recalls sacrificial practices.
She inspired the swamp monster Meg Mucklebones in Ridley Scott’s 1985 fantasy film Legend.