"The Frog Prince" or "Iron Henry" is a fairy tale, best known through the Brothers Grimm's written version; traditionally it is the first story in their collection. - Although the story is best known today through the Grimm Brothers' rendition of it, parts of it may extend back until at least Roman times; a version of the story is apparently referred to in Petronius's Satyricon, in which the character Trimalchio remarks that, "qui fuit rana nunc est rex" ("The man who was once a frog is now a king."). Other scholars, however, argue that this may actually be a jab at the emperor Nero, who was often mockingly compared to a frog.

In the tale, a spoiled princess reluctantly befriends the Frog Prince (meeting him after dropping a gold ball into a pond), who magically transforms into a handsome prince. Although in modern versions the transformation is invariably triggered by the princess kissing the frog, in the original Grimm version of the story the frog's spell was broken when

the princess threw it against a wall in disgust...