Leisel Marie Jones, OAM (born 30 August 1985) is an Australian former competition swimmer and Olympic gold medallist. A participant in the 2000 Summer Olympics – at just 15 years old – and 2004 Summer Olympics, she was part of gold-medal-winning Australian team in the women's 4×100-metre medley relay at the Athens Games in 2004 and a gold medalist for 100-metre breaststroke in the 2008 Summer Olympics in Beijing.
On 17 March 2012, Jones earned selection to compete at the 2012 Summer Olympics in London, and became the first Australian swimmer to compete at four Olympic games. There, she won her ninth Olympic medal, a silver medal in the 4×100-metre medley relay.
Jones is noted for employing a classic breaststroke technique, typified by a slow but deeper stroke cycle and also by her slow starts. Along with South African champion Penny Heyns, she is regarded as one of the greatest breaststroke swimmers ever.