It always for me. I searched a bunch to find the pic I have XD

I do have a question. The aliens, would they look like humans, just with something to tell them apart from humans, say a marking? Or a hair color or eye color? Or maybe a mix of all three? Or would they look completely different and have the ability to somehow make themselves look human, like a natural ability to switch forms or some sort of a cloaking device? Or would they not look like humans at all?