Ellen Marie Estes (born October 13, 1978 in Portland, Oregon) is an American water polo player, who won the silver medal at the 2000 Summer Olympics. She also won a bronze medal at the2004 Summer Olympics. Estes scored three goals during the bronze medal game against Australia. In 2003, Estes was named the USA Water Polo Female Athlete of the Year. From 2007-2009, Estes served as a volunteer assistant coach for the Harvard University Men's and Women's Water Polo Teams, while finishing her MBA at Harvard Business School.