Skyrim has a ton of content and the lore of the game is so rich because it builds from the preceding Elder Scrolls games. With so much to work with, the creators were able to do more than just make a game – they wrote an obscene number of stories to flesh out their world. Reddit user OccupyTamriel made a gallery of the fictional authors of these books (images above) from in-game shots.
At UESP they have a catalog and text of every book in Skyrim. One fan went as far as creating an ebook file that contains all the books: Dovahkiin Gutenberg.