John Heaton (1818–1897) was a 19th-century mechanical engineer who lived in England. Government documents refer to him at different times as a civil, mechanical and mining engineer, reflecting the breadth of his work. He is mainly known for inventing the Heaton process, a way to convert cast iron into steel, and his subsequent legal battles with fellow Englishman Henry Bessemer, who had developed a different method for the same conversion. He later obtained a patent regarding efficiency improvements in steam boilers.