kobold
An ambivalent, sometimes vindictive, spirit that is capable of materialising as an object or human, often a child; a sprite.
At this point a cock crew, and the youth jumped up hastily saying : 'Of course I shall ride with the king to the war, and if I do not return, take your violin every evening to the seashore and play on it, so that the very sea-kobolds who live at the bottom of the ocean may hear it and come to you.'
1904, Andrew Lang (collector), author and translator not identified, The Mermaid and the Boy, The Brown Fairy Book, page 176,A mischievous elf or goblin, or one connected (and helpful) to a family or household.
When the Kobold is about coming into any place, he first, in this way, makes trial of the disposition of the family.
One of a diminutive and usually malevolent race of beings, often with a reptilian or dog-like appearance.
There were also various trolls like great smiling badgers, brownies darting about laughing, dwarves with large gray heads, sensuous mermaids, stony kobolds, green gnomes, sirens and many elves, who were busy purifying the sacred hilltop in a mythological cooperation marvelous to the soul's perception.
Where it comes from
Borrowed from German Kobold. Doublet of cobalt.
Adapted from the Wiktionary entry kobold (CC BY-SA 4.0).