Last-minute book-inspired costume ideas for the truly lazy (Part I)

Let's start with the kids, shall we?

Pre-Hogwarts Harry Potter:
This one couldn't be easier, less expensive, or more cold-weather-friendly. Dress your kid in oversized, shabby clothes, slap some tape on a pair of non-prescription glasses, draw the scar, and you're done.

Nancy Drew:
A red wig or red-tinted hair spray, a flashlight, and a magnifying glass. (Bonus points for a shirtwaist-style dress, but it's totally not necessary.)

Calvin from Calvin and Hobbes:
Some serious hair gel to achieve that unique Calvin coiffure, a striped t-shirt, a stuffed tiger, and you're golden!