Greys are beings alledgedly from the Zeta Reticuli and Orion star systems, there are many variants of the Grey including hybrids of Humans and other
Aliens.
They are obviously Grey in color but their color and shape depends and could be racial or genetic, they range from 3~5 feet tall generally but there
are other tall greys that are in the 6 feet range, they have long arms like Apes, their hands have four digits and their feet generally have less than
that, usually 3, their eyes reportedly are covered by large oval shaped lenses, under that they alledgedly have reptillian like eyes with vertical
slit pupils.
They don't appear with sex organs most of the time but variants are reported to exist with genitalia, some say they are naked, others claim they are
in jumpsuits or spacesuits, they often have little or different emotion compared to us, they rarely make audible sounds.
Their star system is claimed to be Zeta Reticuli, the correct name of a Grey would be Zetan according to human naming however the government simply
refers to them as EBE's (Extra-Terrestial Biological Entities) or according to some EBEN (probably slang).
There are three distinct types,
Type A
The most common and has been claimed to be filmed in the
Alien
Interview Video (not to be confused with the Alien Autopsy which is likely a hoax), they are generally average sized, between 4~5 feet tall and
reportedly came from Zeta Reticuli.
Type B
The large Grey, generally seem more compassionate and seem to be more emotional, they are more frequently reported with genitalia than any other grey,
quite possibly oversee the abductions, visitations and other human related matters.
Type C
The most unpleasant and mysterious greys and are reported to be the most dangerous, these are smaller than average and are more frequently seen in
eastern Europe and Russia, it's unknown where they come from and contact should be avoided with these if possible.
Hybrids
There are Greys that seem to be Hybrids of Humans, Reptillians (Reptile/Dinosaur type alien) and esspecially the Human/Alien Hybrids seem to be the
most pleasant Alien, and visitations of these are nearly always pleasant according to most reports.
Other Aliens
Nordics
Many variants exist, they look the closest to human beings as any other Alien species reported, the most common type is from Pleidas, they are called
nordics because they look like they are from Sweden with their Athletic and tall build, blonde hair and blue eyes, these are often thought to be our
ancestors and possibly decended from the Nephilim, the gods of the Ancient world.
Other common Nordics are from other systems all over the universe and the list is extensive, the Pleidans have reportedly been in contact with Billy
Meyer but unfortunatly it seems to be a hoax, still evidence persist of these species, even by government officials, check the Disclosure project.
Reptillians
Reptillians have 2 common types, they are diversive in their looks but often they are Dinosaur like, much like a Komodo Dragon on their hind legs, I
will cover the two types in detail.
Reptoid, Dinosaur men, Reptillian.
These are reported to be from our own planet, They came about as an inteligent species of Dinosaur and have lived until the great extinsion on the
planet and after that going underground where they live now, they live in underground caverns and reportedly have a second sun under there (according
to Hollow Earth theorist), but likely this is in reference to the magma in the core or some artificial UV lighting which they require, these are
possibly the original Terrans and have been forced underground by the Nephilim.
Draconians
These are the Aliens that caused the Dragon mythology to begin according to theorist, they are Reptile like with wings, often described to be like a
grey but with scales and wings, and are very tall, 8~10 feet is not uncommon, this alien is probably the cause for many mothmen sightings as well,
they are named Draconian since they are reportedly from Alpha Draconis, they seem to rule over the Reptillians and Greys and seem to be at war with
the Nordics and Pleidan people but this is a rumour at best.
The word Draconian came from these aliens since they were cruel and cold conquerers, likely influencing many ancient religions and often referenced to
Wing Serpents and Dragons in ancient lore.
Draconians in myth
Quetzalcoatl in Incan myth was a serpent like creature with wings.
Lilith, Adam's first wife was a serpent like creature and had wings.
Mothman, most famous for the Point Pleasant encounters.
Dragons, from European myth to Asian Myth.
They are too numerous to list, many other Mythologies have these kind of creatures.
In less than 5000 characters I was able to give you a good impression I think.