This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Bluecap (English)
A bluecap is a mythical fairy in English folklore that inhabits mines and appears as a small blue flame. If miners treat them with respect, the bluecaps lead them to rich deposits of minerals. Like knockers or kobolds, bluecaps can also forewarn miners of cave-ins. They are mostly associated with the Anglo-Scottish borders.
Bluecaps were regarded as hard workers and it was said that they were expected to be paid a working man's wages, equal to those of an average putter (a mine worker who pushes the wagons). This payment was left in a solitary corner of the mine, and they would not accept any more or less than they were owed.