Despite its late origin, it grew to become one of the most popular ballads in both Denmark and Sweden. It has been described as the best-known and most widely discussed in all of Danish balladry. During the Danish
Romantic Period, the motif inspired
Jens Baggesen's poem "Agnes fra Holmegaard" (1808) and
Adam Oehlenschläger's "Agnete" (1812).
Hans Christian Andersen worked the material into the play
Agnete og Havmanden (1834) which was staged, accompanied by the music of
Niels Gade, but the show was a flop. It also plays a significant role in Problema III of Kierkegaard's
Fear and Trembling (1843). The ballad was the basis for
Matthew Arnold's 1849 poem "The Forsaken Merman", although Arnold's heroine being named "Margaret" has led to the claim that the actual source might be the folklore account published by
Just Mathias Thiele, where the woman enticed by the merman is named "Grethe".
Poul Anderson wrote a sequel novel ''
The Merman's Children'', about her children. == Outer appearance ==