Mildred Muis (born 28 July 1968 in Amsterdam) is a former medley and freestyleswimmer from the Netherlands, who competed in two consequentive Summer Olympics for her native country, starting in 1988. There she won the silver medal with the Dutch women's 4×100 m freestyle relay team, behind East Germany. Her twin sister and three-time Olympian Marianne was on the same silver winning team.