Leland Ossian Howard, Ph.D., M.D. (June 11, 1857 in Rockford, Illinois – May 1, 1950), was an American entomologist.
He graduated from Cornell University in 1877. He was later employed by the Department of Agriculture, and became chief of the Bureau of Entomology in 1894. He was the editor of Insect Life, lecturer on entomology at several colleges and universities, and a contributor to reference books on the subject of entomology. He was made permanent secretary of the American Association for the Advancement of Science, honorary curator in the United States National Museum, and consulting entomologist of the Public Health Service.
- Mosquitoes, McClure, Phillips & co., 1901
- The Insect Book, Doubleday, Page & Company, 1901
- The House Fly-Disease Carrier, Frederick A. Stokes company, 1911
- Mosquitoes of North and Central America and the West Indies, Authors Leland Ossian Howard, Harrison Gray Dyar, Frederick Knab, Carnegie Institution of Washington, 1917
- Fighting the insects: the story of an entomologist, MacMillan, 1933
- "Leland Ossian Howard Centennial 1857-1957", Bishopp, Fred Corry, Bulletin of the ESA, Volume 3, Number 3, September 1957, pp. 1–3(3)