From the Greys to the Nordics, these aliens appear frequently across abduction stories and science fiction tales.

Avi Loeb, a Harvard astronomer who has made headlines with his theories about alien encounters, will lead a White House scientific advisory council on UFOs.

Devils Tower, Wyoming (CNN) — The buzz started in a hay meadow at the foot of a mysterious-looking geological formation. Helicopters and trailers arrived in large numbers, famous faces and a ...