John Grundy Jr. (1719–1783) was an English civil engineer, who worked on a number of drainage schemes, canal projects and dock works. He lived in Spalding, Lincolnshire, from 1739. Part of his legacy was his Report Books, seventeen volumes containing copies of his reports and other supporting documents from most of his projects, which in some cases are the only surviving records of major civil engineering projects. They were re-discovered in 1988.