Ernest Thomas Gilliard (23 November 1912 – 26 January 1965) was an American ornithologist and museum curator who led or participated in several ornithological expeditions, especially to South America and New Guinea.
He began a lifelong association with the American Museum of Natural History (AMNH) in New York in 1932 by working there as a volunteer.
New Guinea, and especially its birds-of-paradise and bowerbirds, kept drawing him back, and he led a total of five expeditions there, his final one in 1964.
In addition to numerous papers in the scientific publications of the AMNH, he wrote many illustrated articles for Natural History and the National Geographic Magazine.
Gilliard was an expert photographer and cinematographer; he was involved in making the documentary Search for Paradise (1957), which was directed by Otto Lang.