Giselbert van Loon (probably died about 1045) is the first definitely known count of the County of Loon, a territory which, at least in later times, roughly corresponded to the modern Belgian province of Limburg, and generations later became a lordship directly under the Prince-bishopric of Liège. Very little is known about him except that he had two brothers, one of whom, Bishop Balderic II of Liège, is much better attested in historical records.