Grey aliens (also referred to as "Roswell Greys", "Greys" or "Grays") are alleged extraterrestrial beings whose existence is promoted in ufological, paranormal, and New Age communities, and who are named for their skin color.
Around half of all reported alien encounters in the United States describe Grey aliens. Such claims vary in every respect including their nature (ETs, extradimensionals, demons, or machines), origins, moral dispositions, intentions, and physical appearances (even varying in their eponymous skin color). A composite description derived from overlap in claims would have Greys as small-bodied sexless beings with smooth grey-colored skin, enlarged head and large black eyes. The origin of the idea of the Grey is commonly associated with the Betty and Barney Hill abduction claim, although skeptics see precursors in science fiction and earlier paranormal claims.
Greys are typically depicted as dark grey-skinned diminutive humanoid beings that possess reduced forms of, or completely lack, external human organs such as noses, ears or sex organs. Their bodies are usually depicted as being elongated, having a small chest, and lacking in muscular definition and visible skeletal structure. Their legs are shorter and jointed differently from what one would expect in a human. Their limbs are often depicted as proportionally different from a human's; their humerus and thighs are the same lengths as their forearms and shins, respectively.
Greys are depicted as having unusually large heads in proportion to their bodies. They are depicted as having no hair anywhere on the body, including the face, and no noticeable outer ears or noses, but only small openings or orifices for ears and nostrils. They are depicted as having very small mouths, and very large opaque black eyes with no discernible iris or pupil. Sometimes Greys are depicted as having no noticeable nostrils or mouths. Also reports of alleged encounters state their height to be 2--4 ft tall
Greys are commonly included in alien abduction claims. Among reports of supposed alien encounters, Greys make up approximately 50 percent in Australia, 43 percent in the United States, 90 percent in Canada, 67 percent in Brazil, 20 percent in Continental Europe, and around 12 percent in the United Kingdom. These reports include two distinct groups of Greys that differ in height. Abductees say that they recognize the leader of their abductors by its "demeanor." Some ufologists and abduction researchers believe that taller Greys, with their reported increased authority and apparently more complex psychology, may be the only Grey type to be biologically alive and that the shorter form could be their artificially constructed robot or cyborg servants
Some alien abduction reports have depicted variant skin colors such as blue-grey, green-grey, or purple-grey and sometimes not grey at all. The skin is typically described as being extremely smooth, almost as if made of an artificial material like rubber or plastic.
Abduction claims are often described as extremely traumatic, similar to an abduction by humans or even a sexual assault in the level of trauma and distress.