Steven Macon Greer (June 28, 1955) is an American ufologist and retired traumatologist who founded the Center for the Study of Extraterrestrial Intelligence (CSETI) and the Disclosure Project, which seeks the disclosure of allegedly classified secret UFO information.

Greer was born in Charlotte, North Carolina, in 1955. He claims to have seen an unidentified flying object at close range when he was about eight years old, which inspired his interest in ufology.

Greer was trained as a Transcendental Meditation teacher and served as director of a meditation organization. He received a B.S. degree in biology from Appalachian State University in 1982 and an M.D. degree from the James H. Quillen College of Medicine of East Tennessee State University in 1987. He attended MAHEC University of North Carolina where he completed his internship in 1988 and received his Virginia medical license in 1989. That year, he became a member of the Alpha Omega Alpha Honor Medical Society.