John William Salter (15 December 1820 – 2 December 1869) was an English naturalist, geologist, and palaeontologist.
Salter was apprenticed in 1835 to James De Carle Sowerby, and was engaged in drawing and engraving the plates for Sowerby's Mineral Conchology, the Supplement to Sowerby's English Botany, and other natural history works. In 1842, he was employed for a short time by Adam Sedgwick in arranging the fossils in the Woodwardian Museum at Cambridge, and he accompanied the professor on several geological expeditions (1842–1845) into Wales.
In 1846, Salter married Sally, daughter of James De Carle Sowerby, and eventually fathered seven children with her. Also in 1846, Salter was appointed on the staff of the Geological Survey and worked under Edward Forbes until 1854. He was then appointed palaeontologist to the survey and gave his chief attention to the Palaeozoic fossils, spending much time in Wales and the border counties. He contributed the palaeontological portion to Andrew Crombie Ramsay's Memoir on the Geology of North Wales (1866), assisted Roderick Murchison in his work on Siluria (1854 and later editions), and Sedgwick by preparing A Catalogue of the Collection of Cambrian and Silurian Fossils contained in the Geological Museum of the University of Cambridge (1873).
Salter prepared several of the Decades of the Geological Survey and became the leading authority on trilobites, contributing to the Palaeontographical Society four parts of A Monograph of British Trilobites (1864–1867). He resigned his post on the Geological Survey in 1863. Salter committed suicide on 2 December 1869 by throwing himself into the Thames, and was buried in Highgate Cemetery.