Reginald of Bar, also known as Renaud de Mouçon, was bishop of Chartres from 1182 until his death in 1217.

His parents were Reginald II of Bar and his wife Adèle de Champagne.

He was named canon and treasurer of Saint-Martin de Tours and was then elected bishop of Chartres in 1182.

[2] Returning to France, in 1199 he negotiated the marriage of Theobald III of Champagne to Blanche of Navarre.

After Theobald's death and during Blanche's regency, he held great influence in the court at Champagne.