Steven Macon Greer is an American ufologist and retired physician who founded the Center for the Study of Extraterrestrial Intelligence (CSETI) and the Disclosure Project, which seeks the disclosure of alleged classified UFO information.

Ufology is the investigation of unidentified flying objects (UFOs) by people who believe that they may be of extraordinary origins. While there are instances of government, private, and fringe science investigations of UFOs, ufology is generally regarded by skeptics and science educators as an example of pseudoscience.