Merriam, Clinton Hart (1855-1942), was an American physician and zoologist. His expeditions for wildlife study in the western United States led to a compilation of data that helped to define the geographic distribution of animals and plants throughout the country. He later studied the Pacific Coast Indians. He also was a founder of the National Geographic Society in 1888.

Merriam's interest in nature began early and, at age 12, he began collecting birds and insects, and soon included reptiles, mammals, plants, and marine invertebrates. In 1872, he joined the Government Survey of the Territories (also known as the Hayden Survey) and collected many birds in Utah, Idaho, and Wyoming.

Merriam studied at Yale University, Connecticut, and earned an M.D. degree at Columbia University's College of Physicians and Surgeons in New York City in 1879. In 1885, he gave up medicine and devoted himself to natural history.

In 1885, the entomological division of the U.S. Department of Agriculture (which later became the United States Bureau of Biological Survey, now known as the U.S. Fish and Wildlife Service) was established, originally to survey bird distribution in the United States. Merriam served as the bureau's director until 1910, and under his guidance the agency was expanded to also include the study of plants and animals. He also was instrumental in establishing federal responsibility toward wildlife conservation by helping to secure the Lacey Act of 1900, which prohibited interstate commerce in illegally killed game and regulated the importation of foreign species.

In 1899, Merriam organized and directed an expedition to Alaska sponsored by railroad financier Edward H. Harriman. The resulting compilation of the data gathered is of value to conservationists today. Around that time, Merriman developed his “life zones” theory, which stated that temperature patterns determined the geographic distribution of plants and animals.

During his later years, Merriman became interested in Western Indian tribes, and he published several articles and books on Indian culture and language. His book, Studies of California Indians, was published in 1955.