Kornelia Ender (later Matthes now Grummt, born 25 October 1958) 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.

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.

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.

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.

[2] Ender was married for four years to East German backstroke swimmer and multiple Olympic champion Roland Matthes.