Robbie as Colonel Roy Mustang. I may be biased, but I think he is rather frighteningly good looking in a uniform.
Good looks were obviously not relevant to Aaron's Xenomorph costume. He had literally not an inch of skin showing. Unfortunately, he also couldn't see all that well, since the eye holes are little vertical slits beside the internal mouth. The tail didn't last the evening either, it ripped off its mounting and had to be left home - which was probably just as well, because with the lack of peripheral vision, Aaron couldn't see what was beside or behind him, and kept whapping things with it. He did get a lot of compliments, though several people thought he was a Predator rather than an Alien. Light trick-or-treating this year for some reason - we still have about half of our candy, and usually we get cleaned out.
