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

There are claims that Trump was briefed on Greys, Nordics, and human hybrid aliens. The White House, Public domain, via Wikimedia ...

For more than 70 years, the image of the Grey alien has haunted human imagination. Oversized black eyes. Smooth grey skin.

A former CIA-linked physicist's comments about 'four alien species' have reignited UFO conspiracy theories online.