Your mind was blown when you found out the Cat in the Hat made an appearance in more than one book, right? Well, get ready for this: he's actually in six—count 'em, six—Seuss masterpieces. (Source)

One of Seuss's many trademarks is that he doesn't use too many straight lines. Go ahead, take a look. We bet you can count 'em on one hand. (Source)

Theodore Geisel wrote under a whole slew of pen names, including Dr. Seuss, Theo LeSieg (Geisel spelled backwards), Rosetta Stone, and one of our favorites, Theophrastus Seuss. (Source)