| Marie, Countess of Ponthieu | |
| Father: | William IV of Ponthieu |
| Mother: | Alys, Countess of the Vexin |
| Spouse: | Simon of Dammartin Mathieu de Montmorency, Seigneur d'Attichy |
| Issue: | Joan of Dammartin Mathilda of Dammartin Philippe of Dammartin Maria of Dammartin |
Marie of Ponthieu (17 April 1199 – 21 September 1250) was suo jure Countess of Ponthieu and Countess of Montreuil, ruling from 1221 to 1250.
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.
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:
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.