Celina Johanna Maria Lemmen (born March 2, 1985) is a Dutch swimmer who specialized in freestyle events. She is a single-time Olympian (2004), and a double medalist in sprint freestyle at the 2001 European Junior Championships in Valletta, Malta. She attended Southern Methodist University in Dallas, Texas, where she majored in management, and swam for the SMU Mustangs under head coach Steve Collins. While studying in the United States on an athletic scholarship, Lemmen has earned numerous high school and state titles, and received two-year All-American honors in college swimming.