Everybody's favorite alien. It seems that these guys are pretty darn popular. Which doesn't make much sense, since they're the ones that are usually said to abduct people and most definitly  put anal probing on the map.

The greys have big bald heads. Their bodies are usually frail, and skinny. The skin color is usually some shade of grey. They have three fingers and a thumb, and I heard somewhere that they don't have palms; the fingers come out of the wrist.  The Grey comes in a variety of sub-species listed below:

Calista Grey Type A

Possibly Most Sinister Form of the Infamous Grey Extraterrestrials.
Belived To Be Incapable of Ingesting Earth Food

Known primarily for it's willingness to mate with anything that moves, this frail ET has been responsible for a virtual lexicon of alien knowledge regarding the human rectal tract.  But with the Calista Grey Type A, anal probing is only the beginning of its bizzare un-earthly behavior.  The Calista Grey Type A has a difficult time ingesting nutrients and will often purge after its daily meal.  The Calista Grey Type A is credited with a high inteligence and could possilbly be part of a pre-invasionary force.

Leonardo Passive/Submissive Type Grey

Leonardo Type Passive Grey of the Slave Labor Class

Leonardo Type Passive Greys are very similar to the Calista Grey Type A. They have big awkward, oversize heads and large round eyes. But these guys are more fetus-like in appearance, and have sickly pinkish skin resembling Fuji the Man-Child of Borneo. Due to their limited mental capacities they are exceptionally submissive and all to willing to carry out the dirty work for the Calista Grey Type A species so don't be surprised to see the Leonardo Type Passive Grey brandishing a probe as he crashes your next camping trip or barn raisin party.