| Arnold I, Count of Loon | |
| Birth Date: | 1045 |
| Death Date: | 1125 |
Arnold I (b. about 1045 - d. about 1125), Count of Loon (Looz) from about 1079, son of Emmo, Count of Loon, and Suanhildis, daughter of Dirk III, Count of Holland, and his wife Othelandis.
He was an ally of Henry of Verdun and Otbert, both bishops of Liège. In 1078, he endowed the collegiate churches of Huy and of St. John at Liège.
In 1088, he negotiated at the request of Bishop Henry of Verdun to end a conflict in the abbey of Sint-Truiden where the bishop and emperor Henry IV had appointed rival abbots. As a result of his diplomacy, the emperor transferred the authority of the abbey from Henry I, Duke of Lower Lorraine, to Arnold. Arnold forced Henry and his ally Godfrey of Bouillon, to withdraw from the monastery.
The domain of Arnold expanded with the County of Rieneck by his marriage to Agnes of Mainz, daughter of Gerhard I, Count of Rieneck, and Helwig von Bliescastel. Sources disagree on their number of children, but they are believed to include:
Another son, Gerard, did not exist. He appears in older books such as the oldest edition of Belgian National Biographies, based upon a charter of 1101. Baerten (1969 p. 40 footnote 2) describes this as a mistake caused by modern edition with a wrongly placed comma, and gives references to the literature. While the confusion about the non-existent "Gerard" remains, Arnold is now understood to have been succeeded by his son Arnold as Count of Looz upon his death.