Robert Morton Nance (1873–1959) was a British writer and leading authority on the Cornish language, a nautical archaeologist, and joint founder of the Old Cornwall Society.

Nance wrote many books and pamphlets on the Cornish language, including a Cornish dictionary, which is a standard work, and edited magazines and pamphlets about Cornwall, including Old Cornwall, the journal of the Federation of Old Cornwall Societies. Nance was also a nautical archaeologist of distinction and was an originator of the Society for Nautical Research. His insight and learning were displayed in his book Sailing-ship Models which appeared in 1924. He studied art in Britain and France and was both a painter and a skilled craftsman.