Joan of Châtillon (died 1292) was countess of Blois from 1280 to 1292, and lady of Avesnes.
She was the daughter of John I and Alix of Brittany, Dame de Pontarcy. Her maternal grandparents were John I, Duke of Brittany, and Blanche of Navarre.
In 1263, Joanne married Peter of Alençon, a son of King Louis IX of France and Queen Margaret of Provence. They had 2 children, Louis (1276—1277) and Philippe (1278—1279), who died young. Peter died in 1284.
Joan received the County of Chartres from her father during his life; she later sold these lands to Philip IV of France in 1291. She ceded the lordship of Avesnes to her cousin Hugh before her death. When she died in 1292 the other titles were left to him, too.
| Preceded by John I |
Countess of Blois 1280–1292 |
Succeeded by Hugh II |
| Countess of Chartres bef. 1278 – 1280 |
merged with Blois; to royal domain in 1291 |