elf

In early Germanic folklore, a dwarfish supernatural being. Elves were believed to be mischievous characters who often interfered in human affairs.

They stole young children, swapping them for changelings; they visited people in their sleep and gave them nightmares, and sometimes inflicted them with diseases; and with their elf-bolts they struck down human beings and cattle alike. They also elf-locked women's hair, tangling it into a matted mess, which it was considered unlucky to undo.