Reginald I (also called "the One-eyed", Reinald I, Renaud I) was Count of Bar (1105–1149). Barrois, during the Middle Ages, was the territory of the counts and dukes of Bar, in the eastern part of present-day France, bordering Lorraine.
He was the son of Thierry de Mousson and Ermentrude of Bourgogne, the daughter of William I the Great, Count of Burgundy.
Reginald was one of the leaders of the Second Crusade in 1145. He was drowned somewhere in the Mediterranean Sea on his return voyage to Europe on or before 10 March 1149.
Reginald I of Bar succeeded Theodoric II of Bar (r. 1092–1105) and was succeeded by Reginald II of Bar (r. 1150–1170) in 1150.
| Preceded by Theodoric II of Bar |
Count of Bar 1105–1150 |
Succeeded by Reginald II of Bar |