DeWitt Webb (December 19, 1840 Clinton, Oneida County, New York – April 12, 1917 St. Augustine, Florida) was a physician, politician, and naturalist.

He was the founder, and for 34 years President, of the St. Augustine Historical Society and Institute of Natural Science.

Webb practiced medicine in Salt Point, New York.

He was also the Acting Assistant Surgeon and Medical Officer at Fort Marion at the time when Native Americans lived there during the 1880s.

Webb was a member of the Florida State Legislature and Mayor of St. Augustine in 1911 and 1912.