There are several sub-types of the greys.All tend to appear greyish in color and for this reason are reffered to as "greys". They have large heads and black "wrap around"eyes.They have limited facial features,slit for a mouth and no nose to speak of.They have evolved beyond the need for reproductive systems or digestive systems and reproduce by cloning.Their genetics are partly based on insectoidal genetics.Their science deals largely with the study of other life forms and genetic engineering.They have supposedly had a part to play in the alteration of human genetics over thousands of years.It seems that they may be trying to cross breed with humans in order to create a "mixture race" that would be better than either.They seem to be emotionless and therefor are seen as cruel in their treatment of human beings.These greys are actually servants to a master race of reptilian-type aliens known as the Reptilians.