James Charles Cox (21 July 1834 – 29 September 1912) was an Australian physician and conchologist.
Cox was born at Mulgoa, southwest of Sydney where he played with Aboriginal children and learned from them about native birds and animals. He was educated at the local parish school and the King's School, Parramatta. He was apprenticed to be a physician for three years and learned dispensing at the Sydney Infirmary, acted as a clinical clerk, assisted at post mortems and was present at one of the first operations using chloroform in 1852. He became an assistant to Professor John Smith, the foundation professor of chemistry and experimental physics at the University of Sydney at its original site near Hyde Park, now occupied by Sydney Grammar School and established what became the Sydney Museum next door. He earned an M.D. in 1857 and F.R.C.S. in 1858 at the University of Edinburgh. He married Margaret Wharton in September 1858 and they eventually had four sons and six daughters, one of whom married Montague Bertie, 12th Earl of Lindsey. He was registered as a medical practitioner in New South Wales in February 1859 and developed a lucrative private practice in Sydney.
Cox retained an interest in nature all his life. He was elected a fellow of the Royal Society of New South Wales (then the Philosophical Society) in 1859. He was first president of the New South Wales Board of Fisheries and first secretary of the Entomological Society (later the Linnean Society of New South Wales), both in 1862. He was elected a fellow of the Linnean Society of London in 1868. He was a trustee of the Sydney Museum and left it his collection of land shells. His wrote extensively in the journals of these societies on the conchology of Australia and Melanesia.