Arnold I (1060 - 1135), Count of Looz (Loon) (1078-1135), Count of Hesbaye, and Lord of Horn, 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 Church of Huy and that of St. John at Liège.
In 1088, he spoke on the request of Bishop Henry of Verdun to end a conflict in the Abbey of St. Truiden where the bishop and emperor Henry IV had both appointed a successor abbot. As a result of his diplomacy, the emperor transferred the authority of the abbey of Sint-Truiden 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.
Arnold married Agnes von Mainz, daughter of Gerhard I, Count of Rieneck, and Helwig von Bliescastel. Sources disagree on their number of children, but are believed to include:
- Gerard (d. 1103), possibly Count of Looz for a brief period
- Arnold II, Count of Looz
- Gertrude van Loon (1100-1154), married to Hugo XI, Count of Dagsburg. Their son was Hugo XII, Count of Dagsburg, who married Luitgarde, widow of Godfrey II, Count of Louvain. She was daughter of Berengar II of Sulzbach, and sister of Gertrude von Sulzbach, wife of Conrad III of Germany, and Bertha, wife of Manuel I Comnenus, the emperor of Byzantium. Their granddaughter was Gertrude of Dagsburg, wife of Theobald I, King of Navarre.
- Agnes van Loon (b. ca 1100), married Gerhard IV, Count of Jülich
- Beatrix van Loon (d. after 1132), married Arnout III, Count of Aarschot and had issue.
While the question of Gerard’s countship remains, it is believed the Arnold was succeeded by his son Arnold as Count of Looz upon his death.