The « black knight » is a classic literary character who conceals his identity and that of his liege by not displaying a heraldic emblem. Black knights are generally portrayed as evil characters who take advantage of this anonymity to commit their misdeeds.
In the case of Walter Scott’s famous novel, the black knight is none other than Ivanhoe himself, and Reginald Front-de-Bœuf is the lord who usurped his fief while Ivanhoe was away fighting in the Holy Land alongside Richard the Lionheart.