Walter I of Brienne (10201089), was a count of Brienne and Bar-sur-Seine. He was the son of Engelbert IV of Brienne, count of Brienne, whom he succeeded. He attended the council of Senlis in 1048 and was excommunicated in 1082.
Born in 1020, Walter was the son of Engelbert IV of Brienne and Pétronille. He became count of Brienne on the death of his father around 1035.
On 22 May 1048, he attended the council of Senlis, presided over by Guy of Châtillon, bishop of Reims, and King Henry I of France.
Around 1082, Walter was in dispute with the Abbaye of Montier-en-Der. Theobald III, Count of Blois, was obliged to intervene and requested Hughes of Die, legate of the pope, to excommunicate Walter.
Walter married Eustachie de Tonnerre, daughter of Milo III, count of Tonnerre and 'Azeka. They had the following children: