William de Braose was the son of Reginald de Braose by his first wife, Grecia Briwere. He was an ill-fated member of the House of Braose, a powerful and long-lived dynasty of Marcher Lords.
Arms attributed to William de Braose by Matthew Paris: Party per pale indented gules and azure. Marginal drawing of an inverted shield referring to his Nota impiam murthram ("impious murder")