In To Kill a Mockingbird, readers finally get to see what Boo Radley looks like (chapter 29). He is said to have "sickly white hands that had never seen the sun, so white they stood out garishly against the dull cream wall” (362). In other words, he is almost ghost-like. This is reinforced by his name, Boo. He's a 'shadow' of a person and so his appearance also mimics this.