Ralph I, Count of Vermandois

Ralph I of Vermandois (French: Raoul Ier "le Vaillant") (d 14 October 1152) was Count of Vermandois. He was son of Hugh I, Count of Vermandois, and Adelaide, Countess of Vermandois. By his father, he was grandson of Henry I of France, while his mother had been heiress to Herbert IV of Vermandois.

His only paternal uncle was Philip I of France. Through him Raoul was a first cousin of Louis VI of France and a first cousin, once removed of Louis VII of France.

Ralph served as the seneschal of France during the reign of his cousin Louis VII. Under pressure from Queen consort Eleanor of Aquitaine, Louis allowed him to repudiate his wife Eleanor, daughter of Stephen, Count of Blois and Adela of Normandy and sister of the reigning King Stephen of England, in favor of Eleanor of Aquitaine's sister, Petronilla of Aquitaine. This led to a war with Theobald II of Champagne, who was the brother of Ralph's first wife Eleonore. The war lasted two years (1142–44) and ended with the occupation of Champagne by the royal army.

Ralph and Petronilla were excommunicated by Pope Innocent II for a marriage deemed illegitimate, overriding three bishops who had already annulled Ralph's prior marriage. The excommunication was dropped and Ralph's marriage sanctified a year later in 1143 by Pope Celestine II after Innocent died.

Family and children
Ralph was married three times:

1. in 1125 to Eleanor, daughter of Stephen II, Count of Blois. Their marriage ended in divorce in 1140 and she died in 1147.

2. in 1140 to Petronilla of Aquitaine; they had three children:
 * Elizabeth (or Isabelle) Mabile, countess of Vermandois and Valois (1143–1183), married Philip, Count of Flanders; no issue.
 * Ralph II, count of Vermandois and Valois (1145–1167), was the first husband of Margaret of Lorraine, later countess of Flanders. He died of leprosy in 1167 without issue.
 * Eleanor, countess of Vermandois and Valois (b. 1148? – d.1213/4). She married four times as follows, but had no issue:
 * 1. Godfrey of Hainaut, Count of Ostervant (d. 1163).
 * 2. before 1167 Count William IV of Nevers.
 * 3. ca 1170 Matthew of Alsace.
 * 4. ca 1175 Count Matthew III of Beaumont-sur-Oise.

3. in 1152 with Laurette of Flanders, daughter of Thierry, Count of Flanders and Swanhilde. They had no children.