De Cost Smith (1864–1939) was an American painter, illustrator, and writer whose career was dedicated to the study and depiction of Native American life. Born in Skaneateles, New York, near the Onondaga Reservation, Smith developed a close relationship with the Onondaga people from an early age, regularly visiting the reservation and eventually being initiated into the tribe. He studied art in New York and later at the Académie Julian in Paris, where his early paintings of Native American subjects were exhibited at the Salon.
In 1884, Smith made his first journey West, traveling to the Dakota Territory and visiting the Great Sioux Reservation. He subsequently traveled extensively among Native communities, including the Sioux and Crow, learning several Indigenous languages and developing relationships with tribal leaders such as Sitting Bull, Rain-in-the-Face, and Tendoi. His firsthand experiences became the foundation of a wide-ranging body of paintings, illustrations, and writings documenting Native American life. Smith collaborated with fellow artist Edwin Willard Deming and contributed illustrations and articles to Outing and other major periodicals. His work also addressed the displacement of Native peoples and the loss of their lands under U.S. government policies. In 1893, his painting Driven Back was included in the Fine Arts exhibition at the World's Columbian Exposition in Chicago.
Smith continued to combine his artistic practice with writing, collecting, and ethnographic study. He served with the Bureau of Indian Affairs under several presidential administrations, including that of Theodore Roosevelt, and published two books recounting his travels and experiences. A member of the Salmagundi Club and the American Ethnological Society, he exhibited regularly in New York during the late nineteenth and early twentieth centuries. His extensive collection of Native American artifacts was subsequently incorporated into the collections of the American Museum of Natural History and the Smithsonian Institution. Smith died in Amenia, New York, in 1939.