Joanna of Ponthieu was a noblewoman born around 1210 in Ponthieu, a region in northern France. She was the daughter of Count William I of Ponthieu and Aveline of Lancaster. Joanna played a significant role in the political landscape of her time, particularly through her marriage to John of England, which strengthened ties between England and France. Joanna's marriage to John took place in 1220, and they had several children, including Henry III of England. After John's death in 1237, Joanna became a widow and managed her estates. She is remembered for her contributions to the lineage of English royalty and her influence in medieval politics.