One distinct species is mentioned again and again in stories about encounters with aliens. The descriptions of these beings are always strikingly similar: they have a grey skin, are usually about 4 foot tall (though smaller and taller versions have been encountered, too); they have huge black wraparound eyes, hardly any nose or mouth, and their sex is indistinguishable. Because of their grey skin, people started calling them "Greys."

Research has indicated that many of these Greys come from either the Orion Constellation, or from the zeta stars of the Reticulum Rhomboidalis constellation. The Greys coming from Zeta Reticuli are usually referred to as the Zetas. Erroneously, in part of the UFO literature, 'Zetas' has been used as a synonym for 'Greys,' even though they are only one of several known species of Greys. (For more information on Zetas, see Zetas.)

Some believe that the US Government has a secret agreement with the Greys. According to the agreement, the US Government would allow people to be abducted on the condition that they would not be harmed, that they would be returned and that they would not remember the incident. In exchange, the US Government would get highly evolved technology. It is not clear whether this agreement was reached in 1954 (on Feb. 20, at Edwards AFB) or in 1964 (on April 24 or 25, at Holloman AFB).

Types of Greys

The UFO literature usually distinguishes three kinds of greys:

  1. Type A: Common Greys – approximately 4 feet tall,
  2. Type B: Tall Greys – anywhere between 6 to 9 feet tall,
  3. Type C: Smaller Greys – approximately 3 to 3.5 feet tall.

Further research, however, shows that these three categories are insufficient / inadequate to describe the different types that have been encountered. A typology consisting of five main types would be as follows:

  1. Tall Nosed Greys: they are 6 to 9 feet tall, and, unlike other Greys, they have a distinct nose.
    These are sometimes referred to as Eban, and are believed to come from the Betelgeuse system in the Orion Constellation.
  2. Tall Greys: they are 6-7 feet tall, and basically are taller versions of the ‘Standard Greys.’ They have large heads and wraparound eyes, a slit-like mouth.It is possible that we are actually dealing with two different types, because, unlike the ‘Standard Greys,’ some of these Tall Greys are said to have reproductive organs. They also seem to have something that resembles a (small) nose. 
    They are believed to come from the same constellations as the 'standard' and 'short' Greys, mentioned below.
    These are commonly seen during abductions, and abductees often refer to these beings as 'doctors,' or 'diplomats.'
    For what it's worth, both Phil Schneider and Bill Cooper claimed that it is with the Tall Greys that the US Govt. made an agreement, and that they are now instrumental in developing the 'New World Order'.
  3. Standard Greys: This is the most common type. They are about four to four and a half foot tall, with large bulbous heads and wraparound eyes, a slit-like mouth, small ears without earlobes, and no visible nose. Their legs are shorter and jointed differently than one would expect in a human. Their arms often reach down to their knees. These Greys have been seen in many different colours and are generally pale in appearance: grey, white, (pale) blue, (pale) green, (pale) orange, and brown.
    It should be noted that there doesn't seem to be one standard phenotype of these, as they have been observed with many different features: some have hands with fingers, some have claws, some have webs, etc.   It is therefore safe to speculate that, in spite of some apparent physical similarities, the group of Type A Greys actually consists of several different species of Greys, that aren't necessarily related, and that come from different parts of our Galaxy. The Zetas, e.g., come from the Reticulum constellation, and are believed to be of a humanoid descent, whereas other races, e.g. those coming from Draco, Orion and Ursa Maior, are believed to be reptilian species.
  4. Short Greys: these Greys are shorter, about three and a half foot tall. They typically look like shorter, but far more muscular - ‘body builder’ - versions of the Standard Greys. They are said to be extremely aggressive, and generally are believed to be the most dangerous of all grey species. Abductees are told they come from Rigel (per J.D. Stone, V. Valerian) and Bellatrix in the Orion constellation, and are suspected to be saurian / reptilian in nature.
  5. Mini Greys: In recent years, reports have emerged which mention Greys that fit the description of the standard Greys (type 3), but are only two feet in size, instead of the usual four to four and half. 

Note that this classification in all likelihood still is a simplification of the actual situation. Estimates of more than 40 different types of Greys are not uncommon. Several sources also mention all kind of hybrid humanoid/Grey races. (See, e.g., 'Essassani').

Additional Information

It should be noted that not all authors are convinced that all Greys are extraterrestrials. John Mack, Jacques Vallee, Withley Strieber and Graham Hancock, e.g., point at the similarities between the abduction realm and the realms of the fairies and the spirit world that shamans visit. They suggest that greys may be part of a parallel realm or another dimension that has always existed and that always had interaction with our reality.
It should also be noted that it is perfectly possible that if such realm exists, that extraterrestrials might use it to travel to Earth. This indeed is what Shamans all over the world claim. Shamans in Latin America and sangomas in Africa even make a clear distinction between the inhabitants of the other realm, and the aliens that use that realm to come and visit us.

Last but not least: a) remote viewers who tried to discover where the greys are coming from mention that they are coming from three different time eras, i.e. that most of them are coming from different times in the future.
b) some authors believe Greys are not aliens but future humans or future humanoids.
c) some sources mention a "cyborg" type of grey: a small grey that seems to be partly biological (and presumably cloned) and partly mechanical. The remains of some of these would have been found at crash sites.