Kornelia Ender (born 25 October 1958 in Plauen, Saxony) is a former East German swimmer who at the 1976 Summer Olympics became the first woman swimmer to win four gold medals at a single Olympic Games, all in world record times. It was later proven that the East German team doctors had systematically administered steroids to their athletes (albeit without the athletes' knowledge). As she had exhibited symptoms of steroid use in 1976 (deep voice, overdeveloped body), strong suspicion was cast on the validity of Ender's accomplishments.
Ender trained from a young age and won her first Olympic medals as a 13-year-old at the 1972 Olympics in Munich: three silver medals, including one in the 200 m individual medley, finishing behind Australia's Shane Gould. Over the following years she broke 32 world records in individual events, including the four at the Montreal Games. In 1991, she addressed the long-held suspicions about her physical condition at the 1976 Games, acknowledging that team doctors and coaches had given her numerous injections of drugs over the preceding months (cf. doping in East Germany). Ender said that she did not know at the time, nor had she ever subsequently found out, exactly what the drugs were. She said she was told only that the drugs would help her "regenerate and recuperate" and therefore, although she was surprised by the muscle mass she added, she nonetheless attributed it simply to her rigorous training.
When she became suspicious and refused to take Chlorodehydromethyltestosterone in 1977 she was banned from the team by the Marxist authorities.
Ender was married for four years to East German backstroke swimmer and multiple Olympic champion Roland Matthes. She is now married to former East German - German track and field athlete and bobsledder Steffen Grummt.