Grimoire Heart was one of the top three Dark Guilds that the Balam Alliance is comprised of, as well as the one commonly considered the strongest Dark Guild. They serve as the main antagonists of the Tenrou Island Arc of Fairy Tail.
The guild owes its name to the Devil's Heart, an organic device which is the source of Guild Master, Hades' immense power, kept inside the guild's airship. When Grimiore Heart first rumored to have any stable location.
Grimoire Heart was founded by Hades, real name Precht), who was originally the second Guild Master of Fairy Tail and was appointed to such a high position by the guild's founder, Mavis Vermillion. He eventually resigned from the position of guild master and made Makarov Dreyer the new leader of Fairy Tail so he could go on an adventure in X736. During his journey, he traced the origins of magic itself back to Zeref Dragneel and refered to it as the "essence of magic". It's assumed he became corrupted by such power and eventually turned evil and formed Grimoire Heart with the purpose of bringing the Ultimate Magic World into existence. He would go on to travel the world and recruit many powerful mages and wizards to his dark guild such as Ultear Milkovich and organized his seventh strongest warriors into an elite team known as the Seven Kin of Purgatory.
By X784, Grimoire Heart rose to become a powerful dark guild and traveled to Tenrou Island with the sole purpose of defeating Fairy Tail and bring about their desired world. In the ensuing Guild War, Fairy Tail was able to emerge victorious and Grimoire Hear was defeated with many of its strongest warriors having been killed in the ensuing battle. The guild was disbanded, but some remnants continued into X791.
As part of the Balam Alliance and one of the core three that make up the alliance, Grimoire Heart was one of the three most powerful dark guilds in all of Earth Land. The guild had many core members from seven core elite warriors of the seven kin to many other low-ranking members that served Hades. During the battle on Tenrou Island, many of Grimoire Heart's members were powerful enough to defeat Fairy Tail's mages in one on one engagements, including their more powerful members. The Seven Kin of Purgatory alone were some of the best warriors in the guild and proved to be very powerful dark mages and challenges for Fairy Tail's mages such as Erza Scarlet and Gray Fullbuster. Azuma was challenging for Natsu and many of Fairy Tail's mages were defeated, but none were killed while Grimoire Hear saw many of its warriors killed in the Fairy Tail-Grimoire Heart Guild War. The war took a significant toll on the guild and it was disbanded not long after the war, though Rustyrose and many low-ranking members survived and there were active remnants well into X791, the same year Fairy Tail and Tartaros went to war.
- Hades - Guild Master (Deceased)
- Bluenote Stinger - Deputy Commander (Left Guild)
- Seven Kin of Purgatory (Disbanded)
The guild is the main puppeteer behind some events of the manga.
- Puherito, in an attempt to revive Mavis, created Fairy Heart, the unlimited source of magic that caused a global war between the continents of Ishgar and Alakitasia many years later.
- Puherito also abandoned a newborn August (the son of Mavis and Zeref ), indirectly helping to direct him to the chain of events that eventually led him to become one of the Spriggan 12 of Alvaraz alongside his father.
- After leaving Fairy Tail and being immersed in the practices of black magic, Puherito adopted the name of Hades and was bribed by the idea of looking for keys to Zeref's awakening to create a world of magicians. All of which led him to create Grimoire Heart and unleash a series of events that eventually led to the war between the dark guild and Fairy Tail guild.
- Zoldeo killed the Brandish μ's mother, this caused Brandish a desire to take revenge on Layla Heartfilia erroneously (believing she was the culprit) and her daughter Lucy. This fact is also one of the consequences that led the girl to enlist in the Alvarez Empire and become one of the Spriggan 12.
- Ultear has corrupted Jellal's mind and manipulated it for many years, which in the long run led to the events of the Tower of Heaven.
- Ultear, under the guise of Zalty, was also the mind behind the crazy plan of Lyon Vastia to awaken Deliora .
- Both Ultear and Jellal (under the false identity of the his alleged twin Siegrain) have infiltrated the Council of Magic headquarters, climbing their social position to become 2 of the supreme leaders.
At the same time, some former members of the guild also helped to make a significant contribution to saving the situation when everything seemed lost.
- Ultear and Meredy, with Jellal, founded the Crime Sorcière guild to make amends with their criminal past by chasing Zeref and the other dark guilds.
- During the events of the Eclipse portal, Ultear, devoured by guilt, decided to atone for her sins trying to bring back the time at least a moment before opening the portal through the Last Ages spell. In doing so, she had to sacrifice almost all her time aging prematurely and, although she managed to move the world's hands of time back a minute, she managed to save the lives of many magicians and to overturn the clash between the 7 dragons and humans in favor of this last.
- While all Dragon Slayers had been catapulted into the Space between Time to fight the human form of Acnologia and the dragon form started to unleash chaos, Meredy helped Lucy Heartfilia to accumulate enough Magic Power to imprison the dragon inside the Fairy Sphere's spell by linking the girl to all the living beings who, at that moment, were on the continent of Ishgar.