Baird, Spencer Fullerton (1823–1887), a United States naturalist. He was one of the first naturalists in America to formulate and use modern field-research methods. Much of his work was sponsored by the United States government. In 1871, while on the staff of the Smithsonian Institution, Baird became the first head of the U.S. Fish Commission (a forerunner of the U.S. Fish and Wildlife Service). Baird put into practice the scientific management of fisheries. He founded the Fish Commission's laboratory for biological research at Woods Hole, Massachusetts, and persuaded Congress to finance construction of the Albatross, a marine research ship.

Baird was assistant secretary of the Smithsonian, 1850–78, and secretary, 1878–87. Under his direction the Smithsonian's first great collection was assembled. Its nucleus consisted of his own specimens, including mounted animals, fossils, and skeletons; other materials were added through the institution's field-work program, which he inaugurated. Baird was a prolific writer and was especially noted for precision and accuracy of description.

Baird was born in Reading, Pennsylvania. He graduated from Dickinson College and became a professor of natural history there in 1846.

Baird was co-author of A History of North American Birds (1874) and The Water Birds of North America (1884).