Though fictional books pop up in books of every genre, they are most frequently to be found in the fantasy genre. There are few things more tantalizing for the devoted reader than these imagined books, whether they are books of magic, fairy tales, philosophy, or fiction. These are some of the most enticing fictional books I've come across in my own reading.
J. K. Rowling's Harry Potter is loaded with fictional books, each one more enticing than the next, from Madcap Magic for Wacky Warlocks and The Hairy Heart: A Guide to Wizards Who Won't Commit, to Men Who Love Dragons Too Much and cookbooks like Charm Your Own Cheese, not to mention the many Hogwarts textbooks, like Quintessence: A Quest and The Philosophy of the Mundane: Why the Muggles Prefer Not to Know. Rowling has in fact provided us with three real versions of fictional books mentioned in the series: Quidditch Through the Ages, Fantastic Beasts and Where to Find Them, and The Tales of Beedle the Bard. All three of these short works are charming and funny additions to the Harry Potter series.
In the Chronicles of Narnia by C. S. Lewis, there are a number of fictional books. In The Lion, the Witch, and the Wardrobe, Lucy discovers the faun Tumnus's library, which includes Nymphs and Their Ways and Is Man a Myth? But by far the most enticing book described in the series is The Magician's Book, a magical work of spells, enchantments, and a mystical and beautiful story that cannot be remembered, read by Lucy as part of a quest in The Voyage of the Dawn Treader. (Laura Miller has written a wonderful reflection on her complex relationship with the Chronicles, fittingly entitled The Magician's Book - I highly recommend it for fans of the series, particularly those who have felt "betrayed" by a realization of its allegorical religiosity.) I do not however have even the slightest desire to read Prince Caspian's grammar textbook, Grammatical Garden or the Arbour of Accidence pleasantlie open'd to Tender Wits by Pulverentus Siccus.
Susanna Clarke's brilliant alternate history fantasy novel, Johnathan Strange and Mr. Norrell, describes as many alluring books of magic as one could wish for, including, How to Putte Questiones to the Dark and Understand its Answeres, Treatise Concerning the Language of Birds by Thomas Lanchester, and most importantly, The Book of Magic by the Raven King. Yet another tantalizing work of magical lore, The Book of Three, is to be found in Lloyd Alexander's The Chronicles of Prydain. Edward Eager, in the last of his fantasy novels for children, Seven-Day Magic, starts his story with a group of children finding a battered, worn book in the library, which not only records what they say and do, but takes them on extraordinary magical adventures. Another talismanic book, The Neverending Story, the title of both Michael Ende's novel and the mysterious book read by his protagonist Bastian, integrates its reader into itself, until the reader is both protagonist and author, perhaps even the book itself.
In several of Madeleine L'Engle's novels, particularly A Swiftly Tilting Planet and An Acceptable Time, a novel by a character called Matthew Maddox, The Horn of Joy, acts as a sort of MacGuffin in the quests of Charles Wallace and Poly O'Keefe. Though fairly little is revealed about the story, we know that it concerns the early settlement of the American continent and a passionate love story.
Though fictional books in fantasy novels prove particularly fascinating, there are a few particularly tantalizing fictional books in non-fantasy literature. I would love to read A Hundred Saints for Travelers by Dunstan Ramsay, protagonist of Robertson Davies' brilliant novel, Fifth Business, as it sounds like a most fascinating work of hagiography, a genre of which I am rather fond. I am even more enticed by Anthony Trollope's Dickens parody, The Almshouse by Mr. Popular Sentiment, mentioned in the classic novel The Warden - had Trollope actually written it, I would bet that it would have been one of the funniest literary parodies ever written. I would love to read any of these intriguing fictional works, if only they existed.