Elliott Coues (September 9, 1842 - December 25, 1899) was an American army surgeon, historian, ornithologist and author.

Coues (pronounced Cows) was born in Portsmouth, New Hampshire. He graduated at Columbian University, Washington, D.C., in 1861, and at the Medical school of that institution in 1863. He served as a medical cadet in Washington in 1862-1863, an in 1864 was appointed assistant-surgeon in the regular army. In 1872 he published his Key to North American Birds, which, revised and rewritten in 1884 and 1901, did much to promote the systematic study of ornithology in America. In 1873-1876 Coues was attached as surgeon and naturalist to the United States Northern Boundary Commission, and in 1876-1880 was secretary and naturalist to the United States Geological and Geographical Survey of the Territories, the publications of which he edited. He was lecturer on anatomy in the medical school of the Columbian University in 1877-1882, and professor of anatomy there in 1882-1887.

He resigned from the army in 1881 to devote himself entirely to scientific research. He was a founder of the American Ornithologists' Union, and edited its organ, The Auk , and several other ornithological periodicals. He died in Baltimore, Maryland.

In addition to ornithology he did valuable work in mammalogy; his book Fur-Bearing Animals (1877) being distinguished by the accuracy and completeness of its description of species, several of which were already becoming rare. In 1887 he became president of the Esoteric Theosophical Society of America.

Among the most important of his publications, in several of which he had collaboration, are A Field Ornithology (1874); Birds of the North-west (1874); Monographs on North American Rodentia, with J. A. Allen (1877); Birds of the Colorado Valley (1878); A Bibliography of Ornithology (1878-1880, incomplete); New England Bird Life (1881); A Dictionary and Check List of North American Birds (1882); Biogen, A Speculation on the Origin and Motive of Life (1884); The Daemon of Darwin (1884); Can Matter Think? (1886); and Neuro-Myology (1887). He also contributed numerous articles to the Century Dictionary, wrote for various encyclopaedias, and edited the Journals of Lewis and Clark (1893), and The Travels of Zebulon M. Pike (1895).