John Thomas Curtis (September 20, 1913 – June 7, 1961) was an American botanist and plant ecologist. He is particularly known for his lasting contribution to the development of numerical methods in ecology. Together with J. Roger Bray, he developed the method of (now known as Bray-Curtis ordination) with its inherent distance measure, the Bray-Curtis dissimilarity. He was also a "well-known contributor" to the Bulletin of the American Orchid Society.