A children's literature costume round up in honor of the holiday:
From Scholastic: Captain Underpants, Angelina Ballerina, Thing 1 and Thing 2, Very Hungry Caterpillar, Little Miss Spider, and a Wild Thing.
The Pigeon goes trick-or-treating!
Wild Thing! (Actually, Max.)
Thomas and friends rolling along.
Man in the Yellow Hat, dude.
Chicka Chicka...Boom Boom!
Complete with mice?
Plus a helpful article about building your own storybook costume.
But my absolute fave isn't from a book, but from a videogame. Yup, it's a knitted baby Link outfit.