Daphne Helena Koster (born 13 March 1981) is a Dutch football defender, currently playing for Ajax in the Vrouwen Eredivisie. She has also played in the American Women's Professional Soccer (WPS) for Sky Blue FC. A powerful centre back, she is the captain of both the Netherlands women's national football team and Ajax.Koster made her senior national team debut as a 16-year-old in August 1997, against Switzerland.