Isabella, Countess of Brienne

Isabella of Brienne (c. 1305–1360), called the Beautiful Helen, was the daughter of Walter V of Brienne, Duke of Athens. After her father was killed by Catalan mercenaries in 1311, her mother fled with her to France. About 1321 she married Walter III of Enghien and bore him thirteen children; she was widowed in 1345.

When her brother Walter VI fell at Poitiers in 1356, she succeeded as countess of Brienne and titular duchess of Athens. She divided her inheritance among her children; Sohier received Brienne, and she died in 1360.