The Grey Aliens, popularized in mass media, are often considered the archetypal idea of an alien. In ufology, the Greys are a type of reptoid often involved in alien abduction cases. Eye witness accounts simply describe them as being "grey" in color, which has given them their present day moniker. Such popularity has lead to countless homages, parodies, and nods to the idea of grey-skinned alien visitors.
Depiction
The Greys are thin humanoids with grey skin, a large head, large, black, almond-shaped eyes, a pair of small slits in the place of the nose, and a small mouth.
The Bellero Shield
In the early sixties, The Outer Limits presented the episode "The Bellero Shield" revealing a greyish type alien (depicted on the left) that may have been the inspiration for what Barney and Betty Hillthought they saw during their alleged abduction experience. The aliens that Betty and Barney Hill described, while under hypnosis, looked remarkably like the grey creature in "The Bellero Shield". Since the Barney and Betty Hill case, Greys have most often been associated with the alien abductions, a trope that is often repeated in science fiction films and novels.
Solipsi Rai
According to the book, Alien Races by Dante Santori and Petro, the Greys are called the Solipsi Rai, a two billion year old race from the constellation Cygnus and is led by a prominent leader named Ymartyyn. The Greys are often confused with other races such as the Maitre and the Zeta Reticulai (the actual abductors of Betty and Barney Hill) due to similar appearances. The Solipsi Rai, are a peaceful and harmless race that have no colonies and focus more on the development of other planets and races. They do however have one powerful weapon to protect themselves from invaders and is capable of destroying entire ships. One of their ships is responsible for the Roswell incident on July 7, 1947. They have also stated that the human race still has 645 options for the future of their planet, with the correct options depending on their ability to develop space travel.
Sauce: https://extraterrestrials.fandom.com/wiki/Grey_alien
Interesting that Roswell happened shortly after JFK assassination.