I wore my favorite and most straightforward costume, of basic blacks, with a deep black wool hooded cloak, and a mesh cowl that makes my face disappear.
It is full of the win, for 3 reasons
First, I don't have to try to control my affect at all, since people can't see my face.
Second, when people see my looming presence, they often shudder and say "that's CREEPY!". What better reaction to a Halloween costume.
And third and best of all, when I hold still for a minute, I utterly vanish from people's preceptions. I can just stop in a moving crowd, and people flow around me like I'm part of the structure. If I stop and stand against a wall or in a corner, people nearby will react and talk like nobody is there.
It's an interesting space to be in, being the invisible man.