Mark Foster is a retired British swimmer, specialising in butterfly and freestyle at 50 metres. He is a specialist short course (25 metre pool) swimmer. In terms of medals and longevity (1986–2008), Foster is amongst the most successful British swimmers of all-time. He made a comeback at the national championships in July 2007 winning both events he competed in after barely training. He achieved the fifth best time in 2007 in the world at 50 metres freestyle and retired for the second time after the 2008 Olympics.