Kornelia Greßler (born 9 November 1970), usually spelled Kornelia Gressler in English, is a retired German swimmer who won three medals at the 1985 European Aquatics Championships: gold in the 4×100 m medley relay and gold in the 100 m and silver in the 200 m butterfly events. She repeated this achievement at the 1986 World Aquatics Championships. In 1985, she set a European record in the 100 m butterfly (59.35) that stood for more than 10 years.