Christiane Knacke

Christiane Knacke (later Driesener then Sommer, born 17 April 1962) is a retired swimmer from East Germany who specialized in the 100 m butterfly. In this event she won a silver medal at the 1977 European Aquatics Championships and a bronze medal at the 1980 Summer Olympics. She was the first woman to break the one-minute barrier in the event, when she clocked 59.78 on 28 August 1977, setting a new world record.

In 1989 she admitted to using performance-enhancing drugs against her will.

She married twice, changing her last name to Driesener and then to Sommer. Her daughter Jennifer was born in 1983.