John Samuel Enys (21 September 1796 – 29 May 1872) was a British mining engineer and scientist who wrote several important papers on the "duty" of steam engines and other types of power delivery, from water wheels to horses. He also made numerous studies on the extensive mining industry in Cornwall. On the death of his great uncle, Francis Enys in 1821 he inherited the Enys Estate, near Penryn, Cornwall and was appointed High Sheriff of Cornwall in 1824.