Jack Mekler (4 March 1932 – 1 July 2019) was a South African long-distance runner. As a boy in an orphanage, he became a self-taught runner. He was boosted by fierce self-determination that grew out of his lonely and harsh childhood experience.His early life was spent in Johannesburg, where he attended Parktown Boys' High School. He won the Comrades Marathon five times as well as various other marathons around the world. He competed for South Africa in various international games. A 25 km Jackie Mekler race is held annually in Gauteng in his honour.