Princess Ilse is a character of German folklore

German folklore

German folklore shares many characteristics with Scandinavian folklore and English folklore due to their origins in a common Germanic mythology. It reflects a similar mix of influences: a pre-Christian pantheon and other beings equivalent to those of Norse mythology; magical characters associated...

, made famous by Marie Petersen

Marie Petersen

Marie Luise Auguste Petersen was a German author famous for her fairy tale Princess Ilse.Petersen came from a well off family of pharmacists in Frankfurt...

 in 1850. While riding to the chase with her father King Ilsing, she lost the way and came at nightfall to the gates of the fairy world, ruled by the fairy queen. The queen met her kindly and invited to the crystal palace.

The legend was further reflected in Heinrich Heine

Heinrich Heine

Christian Johann Heinrich Heine was one of the most significant German poets of the 19th century. He was also a journalist, essayist, and literary critic. He is best known outside Germany for his early lyric poetry, which was set to music in the form of Lieder by composers such as Robert Schumann...

's Die Ilse.