What is redcap?

A Redcap, is a type of malevolent murderous dwarf, elf, goblin or fairy found in Border Folklore. They are said to inhabit ruined castles found along the border between England and Scotland. Redcaps are said to murder travelers who stray into their homes and dye their hats with their victims' blood (from which they get their name). Redcaps must kill regularly, for if the blood staining their hats dries out, they die. Redcaps are very fast in spite of the heavy iron pikes they wield and the iron-shod boots they wear. Outrunning a redcap is supposedly impossible.

They are depicted as sturdy old men with red eyes, taloned hands and large teeth, wearing a red cap and bearing a pikestaff in the left hand