'The Frog Prince; or, Iron Henry'  is a German fairy tale collected by the Brothers Grimm and published in 1812 in Grimm's Fairy Tales. Traditionally, it is the first story in their folktale collection. 
The Frog Prince is a famous story about a prince who is cursed by an evil witch and turned into a frog. A good princess had to give him one desire in order to break the magic. Fortunately, the kingdom's youngest princess came to play near the lake every day, giving the frog another chance to become a prince.