James Cosmo Melvill (naturalist)

James Cosmo Melvill (1845–1929) was a British botanist and malacologist. He collected plants in Europe and North America, and was president of the Manchester Literary and Philosophical Society from 1897 to 1899. He was a grandson of James Cosmo Melvill (1792–1861).

The World Register of Marine Species mentions 881 marine taxa described by J.C. Melvill, many of which together with Robert Standen (1854-1925). Many of these have become synonyms.