There has always been discussion about the close encounters of the third kind aliens. As far as sightings are concerned, aliens come in all shapes and sizes, from the little green men of Kelly, Kentucky to the 10 foot tall giants of Voronezh, Russia. Some of these seem to be living, breathing beings, and yet some appear to have characteristics of a robot.
Most of us picture alien life the way it's portrayed in movies, where aliens are commonly depicted as human-like forms because they use actors either to play the roles directly in make-up or to be models for computer-generated animation. Also, audiences relate to human-like aliens better than to more exotic, monster-like creatures.
It is up to the reader to come to their own conclusions concerning the plausibility of the existence of the specific 'alien' groups mentioned in the paragraphs below, based on their own review of the evidence and documentation contained in the accompanying files.