Pied Piper of Hamelin

The Pied Piper is the main villain of the legend of The Pied Piper Of Hamelin - although he begins as a hero of sorts, he is said to be a symbolic villain that represents a very real incident in medieval Hamelin in which many children died due to plague or some other catastrophe (the details are not clear): the story of the Pied Piper is said to be an adaptation of the event, with the Pied Piper representing the plague or catastrophe that ultimately took away Hamelin's children.

The Legend
According to legend the Pied Piper was a rat-catcher who was called upon by the citizens of Hameline to clear away a plague of rats, which he did with the aid of a magic flute - which hypnotised the rats and he promptly led them out of the town.

However when the citizens refused to pay the Pied Piper he used his magic flute to hypnotise all of the town's children and took them away just as he had done the rats, depending on the version what occurs next varies in intensity and cruelty - traditionally the Pied Piper is said to led the children into a cave to never be seen again but later additions had such grisly tales as him leading all the children into a river to drown or taking them to a distant land, in some less morbid versions the Pied Piper sets the children free after ordering a large ransom from the town but this goes against the original story, which clearly stated the children never returned (with only three children having been spared, due to varied reasons).

Inspirations
The Pied Piper was likely inspired by a plague that killed many of Hamelin's children, with him representing Death itself - although he may also of represented a historical figure connected to the "Children's Crusade" (though the authenticity of such tales is hotly debated) - others have linked him with a serial-killer or some other malignant force that over time became embodied as the now familiar Pied Piper figure.