Marie, Countess of Ponthieu

Marie of Ponthieu (17 April 1199 – 21 September 1250) was suo jure Countess of Ponthieu and Countess of Montreuil, ruling from 1221 to 1250.

Biography
Marie was the daughter of William IV of Ponthieu and Alys, Countess of the Vexin, and granddaughter of King Louis VII of France by his second wife Constance of Castile. As her father's only surviving child, Marie succeeded him, ruling as Countess of Ponthieu and Montreuil from 1221 to 1250.

Marriages and children
Marie married Simon of Dammartin before September 1208. He was the son of Alberic II of Dammartin and Maud de Clermont, daughter of Renaud de Clermont, Count de Clermont-en-Beauvaisis.

Marie and Simon had:
 * Joan, Countess of Ponthieu (1220–1278), married 1) Ferdinand III of Castile. Mother of Eleanor of Castile, the wife of Edward I of England. Married 2) Jean de Nesle, Seigneur de Falvy et de La Hérelle.
 * Mathilda of Dammartin (-1279), married John of Châtellerault
 * Philippe of Dammartin (-1280), married 1) Raoul II of Lusignan, 2) Raoul II, Lord of Coucy, 3) Otto II, Count of Guelders.
 * Maria of Dammartin, married John II, Count of Roucy

Marie secondly married at some time between September 1240 and 15 December 1241, Mathieu de Montmorency, Seigneur d'Attichy, who was killed in battle at Mansurrah on 8 February 1250 during the Seventh Crusade, led by King Louis IX of France.