The 'Grey's' seem to be a scientifically based society that functions to study other lifeforms. Their main purpose seems to be human study and gentetics, also possible cross breeding with humans. Most of this interaction is accomplished through the eye's. The head is large by human standard. Eye's are generally slanted, large and black.
Nose is usually vague.
2 small nares are visible. Mouth is indicated by a small slit without lips, this appears to be non functional. No teeth in the mouth cavity. The body and head are completely hairless. Torso is described as small and thin, often covered in a metallic garment.