Frederick Samuel Dellenbaugh (1853–1935) was an American explorer, born in McConnelsville, Ohio. He was educated in the United States and in Europe.
From 1871 to 1873, he was artist and assistant topographer with Major Powell's second expedition down the Colorado River. He joined the 1899 expedition to Alaska and Siberia financed by railroad magnate E. H. Harriman. He served as librarian of the American Geographical Society (1909-1911), and became a fellow of the American Ethnological Society. His writings include: