The Deadly Book is a book that is capable of inflicting harm on whoever reads it, which can even result in said reader being killed. However, the book may even inflict harm on others as well.
This can be due to many causes, such as the book being cursed to harm anyone who reads it, or else the book is sentient and really doesn't like being read by anyone.
This may also occur if the book is written in by someone.
Compare Tome of Eldritch Lore, which is when a book contains dark prophecies or spells, but is otherwise not actively harmful to its reader. Also compare Books That Bite, which is when an object (which may or may not be a book) actively attempts to bite at anything around it, and Throw the Book at Them, which is when books are being used as physical weapons.
- The eponymous notebook in Death Note. It does not kill the reader, but anyone whose name is written into it will die, so long as the writer is thinking of their face while writing.
- In The Care Bears Movie, there's an evil book who wants to trick Nicolas, a young apprentice of a magician, into using it to turn everyone in the world into jerks.
- In Discworld, the Library of the Unseen University is full of books that do horrible things to people. In particular the Necrotelecomnicon (Written by Achmed the Mad, who preferred to be known as Achmed the I Just Get These Headaches) will drive mad any man who attempts to read it. Fortunately The Librarian isn't a man (but an orangutan) so he has no problem with it.
- Two cases in Harry Potter and the Chamber of Secrets:
- Ron mentions a book that burns the reader's eyes out.
- Also, Tom Riddle (Voldemort)'s diary, which has been sapping Ginny's life and making her cause the attacks. It was able to do this because Ginny confided a lot of her secrets to the diary by writing them in it, making Riddle able to have influence over her. It's later revealed in the sixth book that the diary is one of Voldemort's Horcruxes.
- In Labyrinths of Echo, the Books of Burning Pages were written by a deranged wizard long ago and scattered throughout the world. The text of each Book adapts to the reader, rapidly sucking them into an illusory world created by their narrative. The readers normally don't realize what's happening (nor that every time they turn a page in real world, it burns up into ash — hence the artifact's name), because the narration always starts with a description of their ordinary life, which quickly goes to hell, first driving them insane, then killing them with a graphic description of their own death. It is believed in-story that the Books' creator made one for every poem he wrote to ensure that every one of his poems would only be read once by a person who was just about to die.
- The Name of the Rose revolves around a book that apparently contains Things Man Was Not Meant to Know; anybody who reads it dies horribly shortly afterward. It turns out that there's nothing mystical about the book itself, but someone has treated its pages with poison to kill off anyone who reads it and prevent its contents getting about.
- Father Brown: "The Blast Of The Book" revolves around a book that is reported to drive anyone who reads even a few words of it to self-destruction.
- House of Leaves contains an odd example, in that a large portion of the book itself is the example. The effects of reading it don't seem to hit people universally, but when they do the results are progressive insanity followed by death. In-universe, it's hard to figure out just how dangerous it actually is, because the only person to suffer ill effects (with the possible exception of its author) is already psychologically unstable.
- The Doctor Who episode "Extremis" revolves around The Veritas, a book which is sealed away in a secret library within the Vatican filled with books that the Catholic Church has deemed heretical, and which drives everyone who reads it to commit suicide. The Veritas contains undeniable proof that the reader, the world and everyone in it are computer simulations, being run by an alien race in preparation for an invasion of Earth.
- Cthulhu Mythos books in Call of Cthulhu:
- Reading most of these books causes the reader to lose points from his Sanity score proportional to the power and usefulness of the book. This can cause insanity (temporary, indefinite or permanent), depending on how many points are lost.
- Some of the contents of the books are dangerous in other ways. For example, reading even a page of The Revelations of Glaaki can cause the reader to become aware of the deity Y'golonac, which allows it to possess and destroy them.
- Dungeons & Dragons:
- Forgotten Realms setting spellbooks:
- The Alcaister has metal pages covered with a colorless and transparent contact poison. This drains one Hit Point each time the reader touches it, and each 5 Hit Points lost causes the reader to temporarily lose a point of Strength.
- The Scalamagdrion. One of its pages is an illustration of a dragon-like monster in a cave. If the picture is watched for too long, the creature will come out of the book and attack the reader.
- Deities and Demigods Cyclopedia. The Cthulhu Mythos section says that anyone who reads one of the Mythos books may change alignment to Chaotic Neutral or go mad. Anyone who reads the Necronomicon itself may suffer a worse fate, such as being torn apart by demons.
- The Codex of the Infinite Planes is a powerful magical artifact. Anyone reading it has a 1% cumulative chance per page of suffering a horrible fate, so if someone reads all 99 pages they are almost certainly doomed.
- Vacuous Grimoire: Anyone who reads this book can lose one point of Intelligence and 2 points of Wisdom.
- There are a number of lesser magical books that often have a negative effect only on creatures of specific classes or character alignments:
- Book of Infinite Spells: Any creature that can't already cast spells takes 5-20 Hit Points and is stunned for 50-200 minutes.
- Book of Exalted Deeds: Neutral clerics, evil clerics, wizards, thieves, assassins and bards take various types of damage from reading it.
- Book of Vile Darkness: non-Evil characters take massive damage from reading it, including being attacked by a night hag.
- Libram of Gainful Conjuration: harms anyone who reads it except a Neutral aligned magic-user.
- Libram of Gainful Conjuration: harms anyone who reads it except an Evil aligned magic-user.
- Libram of Silver Magic: harms anyone who reads it except a Good aligned magic-user.
- Manual of Puissant Skill at Arms: Any magic-user who reads it will be stunned and lose a lot of experience points.
- Manual of Stealthy Pilfering: Any cleric, ranger or paladin who reads it will take damage, be stunned and lose experience points.
- Forgotten Realms setting spellbooks:
- The first few of the Grimtooth's Traps books (collections of traps for tabletop RPGs) had a joke "101st Trap" at the end. Supposedly, Grimtooth had boobytrapped the book somehow to kill the reader.
- Second and Third Edition Nobilis both have flavour text describing a book on the true nature of beauty. Because the book is a sacrosant object not meant for mortals, it kills the first to read any word within. The vignette wraps up with "It is a statement on the nature of beauty, and the nature of scholars, that [...] over half of its text had been read, understood, and transcribed."
- In Final Fantasy Tactics, books cause damage by the user reading from it (or you could Throw it via the Ninja class.)
- In The Witch's House, reading the Book of Death will cause Viola to gouge her own eyes out, killing her.
- The old DOS game Wizard's Castle has 24 books scattered about its eight-level dungeon. Most are harmless: "It's an old copy of Playelf," or "Another volume of Zot's awful poetry." Some can grant a strength boost or enable spell-casting. However, there are books that blind the player character. Stumbling sightless around a dungeon of esurient monsters tends to end badly. A few books will adhere to the player character's hands, rendering it impossible to use a weapon.
- The SCP Foundation has a few of these:
- SCP-140 (An Incomplete Chronicle), a Reality-Writing Book about an extinct quasi-human civilization that practiced such horrors as Black Magic, cannibalism, human sacrifice, etc. Any time it is around any fluid suitable for writing (including blood), it leeches that ink from other books or writing implements and performs a Cosmic Retcon, causing the civilization it describes to last longer in history and become more powerful. It is also capable of causing a dangerous obsession in those who study or possess it to cause them to want to add onto the story. The copy in the possession of the Foundation was found in the home of a history professor, where it had leeched all the ink out of multiple volumes in his possession and finally caused him to slash his own wrists and use his blood as new raw material for the book.
- SCP-241 ("Good Home Cooking") is a cookbook that displays appetizing dishes containing one or more ingredients that the reader is allergic to. If the reader prepares one of said dishes and eats it, they will always die of anaphylactic shock. In addition, it will amplify the reader's existing allergies or induce new ones every time that it is closed and reopened.
- SCP-592 (Inaccurate History Book) is a history book that is capable of inflicting injuries on the reader if they read past a certain point (known as the point of divergence), and said injuries may be from wars that never actually happened. In addition, it can cause the reader to become suicidal and suffer other mental issues if they read a passage that is over 10 years past the PoD.
- SCP-1025 (Encyclopedia of Diseases) is a book containing details of various diseases that gives the reader whatever disease they read about. In reality, it only makes the reader think that they have said disease.