Henry Drummond (1851–1897) was a Scottish scientist and writer. Educated at the University of Edinburgh, he became a minister of the Free Church, and traveled extensively, including a survey of the Rocky Mountains, an exploration in Central Africa, and voyages to Australia and the Far East. He was deeply intrigued by the intersection of science and faith, the subject of many of his lectures and books. His best-known work is the sermon “The Greatest Thing in the World.”