Definition of "redcap"

Lord Soulis he sat in Hermitage Castle, / And beside him Old Redcap sly; — / "Now, tell me, thou sprite, who are meikle of might, / The death that I must die?"

1876: Porter & Coates (pub.), Reliques of Ancient English Poetry

"What's a Brownie?" you say. Oh, it's a kind of a sort of a Bogle, but it isn't so cruel as a Redcap! What! you don't know what's a Bogle or a Redcap!

1890, Joseph Jacobs, English Fairy Tales‎

[…] the goblin had aroused the mercenary's ire. This seemed to bring out a formidable and hitherto unrecognized talent in the taciturn young man."Why cam' ye by my door?" The redcap brandished his pikestaff menacingly.Redcap - A malevolent goblin easily distinguishable by their namesake red cap, fiery red eyes, claws and iron boots. They often appear as little old men, but can run very fast despite the boots. They reside in castles and watchtowers along the English-Scottish border, but will move their residence to avoid detection. They have sharp eagle’s talons which they use for weapons, but can easily be repelled simply by reading holy verse.

2002, Cecilia Dart-Thornton, The Ill-Made Mute: The Bitterbynde‎

After boggarts, they studied Red Caps, nasty little goblinlike creatures that lurked where there had been bloodshed […]

1999 July 8, J. K. Rowling [pseudonym; Joanne Rowling], Harry Potter and the Prisoner of Azkaban (Harry Potter; 3), London: Bloomsbury Publishing