Old Ginny Greenteeth is a river hag of English folklore, known especially for pulling children and the elderly into the water to drown them. Legends of Ginny Greenteeth mostly appear int he areas of Lancanshire, Chesire, and Shropshire, though there are a few mentions of her in other parts of England.
Ginny is said to live in the weeds around stagnant ponds or perhaps in the treetops surrounding them, and when children come too close to her, she reaches out her arms and grabs them, dragging them under. It is also rumored that she preys upon children who don’t brush their teeth, capturing them and dragging them into her pond.
Ginny is pale green with, of course, green teeth; her hair is long and green and her nails are sharp and–you guessed it–green. (Much like Elphaba, Ginny is well-known for her distinct hue. Like Kermit says, it ain’t easy bein’ green.) She is particularly associated with duckweed, a plant that can form over stagnant water—thus making the water look as though it were land.
Mentions of Ginny are mostly found in the 19th and 20th centuries, so she seems to be a fairly recent addition to folklore. Her legends serve in part, of course, to warn children of the danger of drowning. But this water witch is also associated with corruption and what-lies-beneath.