Josef Allen Hynek (May 1, 1910–April 27, 1986) was an American astronomer, professor, and ufologist. He is perhaps best remembered for his UFO research. Hynek acted as scientific advisor to UFO studies undertaken by the US Air Force under three consecutive projects: Project Sign (1947–1949), Project Grudge (1949–1952), and Project Blue Book (1952–1969).

In later years, he conducted his own independent UFO research, developing the Close Encounter classification system. He is widely considered the father of the concept of scientific analysis both of reports and especially of trace evidence purportedly left by UFOs.