“Erklings are elfish creatures, three feet tall on average (making them larger than gnomes) with pointed faces, which have aparticular affinity for the taste of children. Their high pitch cackles are particularly entrancing to children, and they use this to lure them away from their guardians to eat them. These creatures also enjoy shooting darts at unsuspecting victims. Originating from the Black Forest in Germany, the difference between this creature and many others is that they can speak Human-language.
Strict control by the German Ministry of Magic, beginning in the centuries preceding 1927, has greatly reduced the number of Erkling attacks. According to Newt Scamander, the last known Erkling attack was on a six-year-old called Bruno Schmidt. The Erkling in question was killed when Schmidt hit it over the head with his father's collapsible cauldron.”
——Joanne. K. Rowling, “Fantastic Beasts and Where to Find Them”
魔王的题材出自1739年的丹麦民谣《骑者奥卢夫爵士》(Hr. Oluf han rider)。1778年,魏玛古典主义诗人、翻译家、哲学家约翰•戈特弗里德•赫尔德(1744-1803)将这首民谣译成了德语。赫尔德从中获取灵感创作出《魔王之女》——“Erlkönigs Tochter”按字面直译过来是“桤木王(!)之女”——并将它收录在自己编纂的民歌集《诗歌中各族人民的心声》(第二部,第二卷,第27首)中。
为此,J. R. R. 托尔金在塑造他笔下的精灵族时还参考了雅各布•格林对“精灵”一词的注解,《魔戒》的德译者玛格丽特•卡鲁特意按照他在《〈魔戒〉命名指南》中的建议用“Elbenkönig”来描述幽暗密林之王瑟兰迪尔、“Elben”为他的族人(毕竟精灵族拥有过人的智慧并且长生不老,与“小精灵、小仙子”不同),而不是像英文一样,用“有些掉价”的“Elf”。