Derek Clayton, English-Australian runner
Derek Clayton (born 17 November 1942) is a former Australian long-distance runner, born in Cumbria, England and raised in Northern Ireland.

Clayton set a marathon world best in the Fukuoka Marathon, Japan on 3 December 1967 in 2:09:36.4, in what is considered a classic race, the first marathon race ever run in less than two hours and ten minutes.

He went on to break this time at the Antwerp Marathon on 30 May 1969 by more than a minute; this time stood as the world best for nearly another 12 years. His personal best time of 2:08:33.6 is still a world-class marathon time. Clayton represented Australia at the 1968 Summer Olympics in Mexico City, finishing in 7th place (2:27:23). Four years later he finished in 13th place (2:19:49) in the same event.

At the 1971 Australian Athletics Championships, he won the marathon in 2:11:08.8. Two years later, he won the Australian Athletics Championships marathon again in 2:12:07.6.

Clayton was inducted into the Sport Australia Hall of Fame in 1999.