In German and Scandanavian myth, an erlking is a mischievous or malevolent sprite which often targets children.
The name, meaning "elf king", derives from German "Erlkönig" and Danish "Ellekonge".
The Erlking is a poem by Goethe.
In this poem, which has been set to music by various composers, a father whisks his sick son on horseback through a misty night to the doctor, while the Erlking pursues them to take the boy's soul. The boy claims to see the Erlking tempting him with promises of treats in his castle and he is afraid. But his father dismisses these spectres as hallucinations due to the fever.
The Erlking has been interpreted as being a singular being, rather than a collective term, and has also been equated with the devil.
The Harry Potter books feature "erklings " which may be based on erlkings.
