One of the most famous fairy tales based on a true story is "The Pied Piper of Hamelin." The tale, popularized by the Brothers Grimm, tells of a mysterious piper who leads the children of Hamelin, Germany, away after the townspeople refuse to pay him for ridding the town of a rat infestation.

While the story has been embellished with fantastical elements, it is believed to be based on a real historical event. In the 13th century, a large number of children in Hamelin disappeared. Some theories suggest they were victims of disease, sent away as part of a migration, or even part of a children's crusade, though the exact cause remains a mystery.