Not much is known about the appearance of each book, but the book containing E.N.D. is shown as a slightly tatty volume with various rips and tears in the cover. It has Zeref's name written in large black letters on the cover and the spine. On the front cover, there is a picture of a glowing eye in darkness with several wavy lines spiraling inwards towards it.
The books contain knowledge on the Black Arts which Zeref used. Many of the spells known to come from the books involve the creation of Demons. Each Demon is summoned by their own book. Warrod Sequen speculates that one specific book, the book of the most powerful of Zeref's Demons, E.N.D., may be in the possession of Tartaros, a Dark Guild whose members consist of Demons originating from the books, also known as Etherious.
- Lullaby (呪歌 Rarabai): This Demon, usually in the form of a flute that kills anyone who hears its tune besides the player, is said to be from the Books of Zeref, according to Goldmine.
- Deliora (デリオラ Deriora): This Demon is also one from the Books of Zeref.
- Nemesis (天罰 Nemishisu): This spell comes from Chapter 4, Section 12 of one of the books, and allows the user to create Demons from rubble.
- E.N.D. (ＥＮＤ Ī Enu Dī): Is described by Atlas Flame as the vilest Demon from the Books of Zeref. According to him, Igneel tried and failed to destroy him 400 years ago. The Demon's name is an abbreviation for "Etherious Natsu Dragneel", meaning his true identity is Natsu himself.
- Eclipse (エクリプス Ekuripusu) : The Eclipse Gate uses a combination of Magic from the books and Celestial Spirit Magic to enable time travel.
- Tartaros (冥府の門 Tarutarosu): A guild made up entirely of Demons originating from the books, according to Erik.
- Bloodman (ブラッドマン Buraddoman): A part of the Alvarez Empire's Spriggan 12, he was at some point created by Zeref, wielding the supreme collection of all of the Curses possessed by the Nine Demon Gates and their leader Mard Geer.
- Larcade Dragneel (ラーケイド・ドラグニル Rākeido Doraguniru): A part of the Alvarez Empire's Spriggan 12, he was deemed the strongest failed Etherious creation from the multiple attempts at remaking Natsu Dragneel, donning the last name of Zeref as proof of his strength.