Creature
Goblins
Never human. They live in the half-second your mind edits out, and what you’re left seeing is a person.

What they are
Goblins were never human, and they have no Sleep of their own. They live in the auto-corrected gap: the half-second your brain edits out. They are made of the thing you refuse to see.
Wearing people
They came through the crack and crossed all the way into the waking world. There they walk the streets disguised as people, rotten underneath. Your mind edits the goblin out and shows you a gentleman. Sometimes a shop window shows you the rest.
Like the trolls, they bring out the worst in the people around them, and encourage it.