John Ridley (26 May 1806 – 25 November 1887) was an English miller, inventor, landowner, investor, farming machinery manufacturer, farmer and preacher who lived in Australia between 1839 and 1853. He is best known for the development, manufacture and invention of "Ridley's Stripper", a machine that removed the heads of grain, with the threshing being done later by a separate machine. The suburb of Ridleyton in the city of Adelaide, Australia was named for him.