A Knocker is a type of Kobold. They live deep in mines and are good-natured spirits, which point out to miners where the rich veins are by using knocking sound, thus this is where they get the name. Although they are friendly spirits they like to play strange tricks on them. They change their faces to scare them or perform strange dances. The miners must leave part of their food for the Knockers or they become mad and that would be bad luck. The Knockers originate from Cornwall but they are also known as Coblynau or Buccas in Wales.