From what i've been researching -- It's not just the astral plane that many encounter aliens, but also on the physical plane. They move about in both planes.
Grey's are not the only alien.
I do not know how a Reptilian looks like- other than just the part of the hip/thigh/leg I glimpsed standing near my bed when I woke up paralyzed one morning. I was not able to force my head to move far enough to see it's entire body. The skin was deep dark green with reptile scales. Very firm also with no flab or fat.
It was not some lizard but like the greys-- you could tell it had two feet and two arms-- humanoid in appearance.