Edgar Donald Mountain (2 April 1901 – 30 April 1985) was a British middle-distance runner, who competed at two Olympic Games.^[3]

Mountain, born Camberwell, London was educated at Sutton Valence School.^[4]

Mountain finished third behind Bevil Rudd in the 880 yards event at the 1920 AAA Championships.^[5][6] The following month at the 1920 Summer Olympics, held in Antwerp, Belgium, he represented Great Britain in the 800 metres event and finished fourth, setting a British junior record.^[1]

Mountain became the National 880 yards champion after winning the AAA Championships title at the 1921 AAA Championships^[7][8] and successfully defended his title the following year at the 1922 AAA Championships.^[9] He finished runner-up to Cecil Griffiths in the 880 yards in 1923.^[10]

He represented Great Britain for a second time at the 1924 Summer Olympics. After the 1924 Olympics, Mountain settled in South Africa and later became a specialist in South African geological formations and professor at Rhodes University. He discovered several minerals, and one them, mountainite, bears his name.^[1]