Odo, Count of Blois

The County of Blois was originally centred on Blois, south of Paris, France. One of the chief cities, along with Blois itself, was Chartres.

Blois was associated with Champagne Province, the House of Châtillon (who tended to reside in Blois), the Dukes of Brittany and, later, with the French royal family. Theobald I, Count of Blois served as Regent to Drogo, Duke of Brittany. Bertha of Blois, the daughter of Odo II of Blois, became Duchess Consort of Brittany through her marriage to Alan II, Duke of Brittany. Stephen Henry's son Stephen of Blois became King of England. Charles de Blois, son of Guy I, Count of Blois, married Joan of Penthievre, the heiress of John III, Duke of Brittany; together, they became principal protagonists in the War of the Breton Succession. Upon the death of his only son, Guy II, Count of Blois sold the county to Louis I, Duke of Orléans and the county passed to the French royal family.

Blois was important during the Hundred Years' War; Joan of Arc based herself there.

The extent of the county varied over time. The northern portion, bordering on Normandy, was sometimes alienated as the County of Chartres, but the Counts of Blois who possessed it did not use a separate title for it. These lands were finally sold to the crown by Joan, Countess of Blois in 1291. In 1439, the area around Châteaudun was separated as Dunois for Jean de Dunois, appointed Count of Dunois.

House of Blois

• William (???–834), first Count of Blois
• Odo (834–865)
• Robert (865–866)
• Warnegald (878–906), only viscount
• Gello (906–928), only viscount
• Theobald I (928–975), only viscount until 960
• Odo I (975–995)
• Theobald II (995–1004)
• Odo II (1004–1037), also Count of Troyes
• Theobald III (1037–1089), also Count of Troyes
• Stephen Henry (1089–1102), also Count of Meaux
• William the Simple (1102–1107), later Count of Sully
• Theobald IV (1107–1152), also Count of Champagne
• Theobald V (1152–1191)
• Louis I (1191–1205)
• Theobald VI (1205–1218)
• Margaret (1218–1230)
  • Walter (1218–1230)

House of Avesnes

• Mary (1230–1241)
  • Hugh I (1230–1241)

House of Châtillon

• John I (1241–1279)
• Joan (1279–1292)
• Hugh II (1292–1307)
• Guy I (1307–1342)

• Louis II (1342–1346)
• Louis III (1346–1372)
• John II (1372–1381)
• Guy II (1381–1397)

House of Valois

• Louis IV (1397–1407), also Duke of Orléans
• Charles (1407–1465), also Duke of Orléans
• Louis V (1465–1498), also Duke of Orléans
• To the royal demesne.
• Gaston (1626–1660), also Duke of Orléans
• To the royal demesne permanently.