Peg Powler is a local character from the folklore of Pirsbridge (a city in the county of Durham, Northern England, a water demon dragging naughty children into the Tees river. According to Kattarine Briggs (1290: p.323-324), Peg Powler is a relative of Jenny Greenteeth, true-bred water-demon, though, according to the Denham Tracts, she must be rated as a nursery bogie:

Peg Powler is the evil goddess of the Tees; and many are the tales still told at Piersebridge, of her dragging naughty children into its deep waters when playing, despite the orders and threats of their parents, on its banks — especially on the Sabbath-day. And the writer still perfectly recollects being dreadfully alarmed in the days of his childhood lest, more particularly when he chanced to be alone on the margin of those waters, she should issue from the stream and snatch him into her watery chambers.

Denham Tracts, 1895 (1297: vol.II, p.42)

Henderson gives a more explicit description of the spirit in Folk-Lore of the Northern Counties:

The river Tees has its spirit, called Peg Powler, a sort of Lorelei, with green tresses, and an insatiable desire for human life, as has the Jenny Greenteeth of Lancashire streams. Both are said to lure people to their subaqueous haunts, and then drown or devour them. The foam or froth, which is often seen floating on the higher portion of the Tees in large masses, is called "Peg Powler's suds"; the finer, less sponge-like froth is called "Peg Powler's cream".

Folk-Lore of the Northern Counties by William Henderson (578: p.265)