Greys" are the modern stereotypical alien and their image has replaced "little green men" in popular culture. They represent 3/4ths of the aliens reported in USA (much higher % than in Europe) and are associated with the so-called "alien abduction phenomenon". In UFO abduction lore, Greys have "cookie-cutter" similarity to one another, and are portrayed as biogenetically engineered clones ("androids" a/k/a "biological robots") created to dutifully perform the alien abduction tasks.
Typically, Greys are described as being approx. 1-1.2m (3.5-4ft) tall, with a weight of approx. 40 pounds. Grey (sometimes blue-grey / green-grey) skin. They have a bulbous, hairless head, large in proportion to their body, supported by a thin neck. Their face is dominated by large black eyes, without pupils. They have two nostrils, slit-like mouths and small ears lacking earlobes. Their body is thin and lacks muscular definition. Their legs are shorter and jointed differently than one would expect in a human. Their arms often reach down to their knees, and accounts give them three digits and a thumb on each hand.
UFO researcher Leonard H. Stringfield (1920-1994), used a variety of sources, to build up a composite of the retrieved bodies from crashed UFOs (e.g. drawing). He said his most valuable sources were medical personnel, including at least two doctors who said they had participated in autopsies in the early 1950s. Stringfield presented his preliminary results at a MUFON symposium in 1978 and published 6 "Status Reports" in 1980s. Some descriptions seem to be that of the classic "Greys" often mixed with the "short non-Greys"