Acnologia (アクノロギア Akunorogia), also known as The Black Dragon (黒龍, Kokuryū), and fearsomely reputed as The Black Dragon in the Book of Apocalypse, is a powerful Dragon that assaulted the Fairy Tail Mages on Tenrou Island in the Year X784.
Acnologia is a mastodonic Dragon whose entire upper body is covered in black, round, scales, which, in turn, are decorated by spiraling, blue markings. His lower body, specifically his belly, inner tail, and legs, are gray in color, and appear to be rather smooth. Acnologia's eyes are white and beady, and his head is round and blunt with four, large, elongated plates extending backward. Acnologia's mouth is full of razor-sharp teeth, and, attached to his chin, is a protrusion that resembles an arrowhead. His large wings are feathery in appearance, akin to a bird's, and very similar to fellow Dragon Grandeeney's. The scales disappear at the end of Acnologia's tail, which, in itself, ends in a stinger-esque shape.
His appearance before becoming a Dragon was that of a normal human. In time, however, Acnologia's appearance turned into that which we see today.
When he was human, Acnologia was quite ruthless, bloodthirsty and violent. He killed any and all Dragons he could, ignoring the fact that many were his comrades.
As a Dragon, Acnologia is a recluse, refusing to go into hiding with the other Dragons, and, at the same time, wanting nothing to do with humans, in spite of the fact that he was once one. As Zeref puts it, he sees them as nothing more than pestering insects, ignoring any and all attempts by them to converse, which suggests that Acnologia is highly arrogant, despite his former disposition.
Born as a human over 400 years ago, Acnologia was one of the first Dragon Slayers to come into being, entering the Dragon Civil War on the side supporting coexistence. Acnologia and a group of other Dragon Slayers, however, disregarded the cause their comrades fought for, and killed every Dragon they could, bathing in their blood. Due to the overuse of his Magic, Acnologia's physique eventually turned into that of a Dragon's, and he proclaimed himself to be the Dragon King. This event was forever etched into history as the Dragon King Festival.
For many years, Acnologia roamed Earth Land, reputed as a fearsome Dragon, and was credited with the single-handed destruction of an entire country. At some point in time, Acnologia ran into Gildarts Clive when the S-Class Mage was on his "100-year quest" on Zonia Mountain. In an instant, Acnologia took Gildarts' left arm, left leg, and an unspecified organ, leaving him to die, before flying away. Gildarts, however, managed to survive, albeit with difficulty, leaving him as the first human to ever see Acnologia and live to tell the tale.
Tenrou Island arc
Seemingly beaconed by Zeref, Acnologia arrives on Tenrou Island, wreaking destruction in its wake. Sensing the destructive capabilities the Black Dragon possesses, Makarov enters Titan Mode, attempting to hold the Dragon at bay to allow the other members of Fairy Tail to escape. After a brief struggle, Acnologia, taking advantage of Makarov's previous injuries, knocks the Guild Master to the ground, pummeling him with his claws.
Just as he is about to kill Makarov, Natsu latches onto Acnologia, preventing the killing blow. Despite Acnologia's attempt to rid himself of Natsu, the Fire Dragon Slayer remains latched onto the Black Dragon's scales, demanding that he leave their Master alone. Led by Erza, the other members of Fairy Tail return, aiding Natsu in his assault against the Dragon. As Gildarts notes that Acnologia is simply toying with them all, the Dragon flies into the air, and then proceeds to seemingly obliterate Tenrou Island with his Dragon's Roar. After the deed is done, Acnologia soars off into the distance.
Acnologia appears one more time at the ruins of Cube where the battle between Fairy Tail Mages and Tartarus takes place. As he nears his destination, both Mages and the Demons take notice of his presence. Effortlessly, Acnologia creates huge explosions with his breath, as well as shockwaves with his wings alone, much to the Mages' despair. He approaches Mard Geer and the Demon deduces that the Black Dragon is after E.N.D.. However, Acnologia's rampage is temporarily interrupted, as Igneel, released from within Natsu's body, attacks him, with an intention to stop his rampage. Acnologia and Igneel begin to clash, while all the Mages below watch in horror and awe. After Natsu jumps on Igneel, the latter fires a huge flame blast towards Acnologia, although the beast easily shrugs off the attack and comes out of it unscathed. Acnologia is then later punched by Igneels' version of Fire Dragon's Iron Fist, however he shrugs this attack off as well.
Shortly thereafter, taking advantage of Igneel's worry for Natsu, Acnologia fires a Dragon's Roar at his opponent's head, but misses. Acknowledging Igneel as his enemy, Acnologia speaks to him, citing his displeasure at the existence of Dragons; he ends his comment by saying that he will slay Igneel. As the fight goes on, Acnologia tells Igneel that he won't escape. However, the latter explains that he didn't intend to run, and that he moved so that he can fight without holding back, in order to defeat the other creature. Acnologia, however, says that it won't be a simple defeat, but an one-sided obliteration. Later as the Face bombs across the continent begin to detonate, Acnologia is sent plummeting towards the earth extremely wounded, much to everyone's surprise. His body is then used as a victory stand by Igneel, who announces the arrival of the other Dragon Slayers' foster parents to stop the mighty threat of the Magic Pulse Bomb.
Acnologia doesn't stay down for long though, as he slashes out at Igneel and takes their battle back up into the sky. There, he questions Igneel's motives for having the other Dragons hide inside their foster Dragon Slayer children, and, when Igneel asks if he is scared of E.N.D. reviving, berates the Fire Dragon and declares that all he wants is utter destruction. Acnologia quickly overwhelms Igneel and repeatedly crushes his torso with his claws whilst screaming about destruction; he also derides the Dragon for being the Flame Dragon King yet not being able to fight equally with him and continues his relentless assault. Acnologia is then quickly overtaken by Igneel and loses his left arm, however in return, Acnologia destroys nearly the entire left half of Igneel's torso and then kills him with his Dragon's Roar. With his arm gone and his target slain, Acnologia then leaves Magnolia.
Magic & Abilities
Dragon Slayer Magic (滅竜魔法 Metsuryū Mahō): As one of the first humans who entered the Dragon Civil War, Acnologia was also one of the first Dragon Slayers brought into existence. Over time, however, as he slayed many Dragons, he himself was, eventually, turned into a Dragon due to the overuse of his Lost Magic. It is currently unknown exactly which element Acnologia employs in his casting of Dragon Slayer Magic, however his Dragon Slayer Magic grants him the ability to reap the souls of Dragons, leaving them in a half-dead state.
- Dragon's Roar: Like all Dragons and Dragon Slayers, Acnologia can perform a Dragon's Roar, incorporating his respective element into the attack. While which element Acnologia employs is currently unknown, the blast was powerful enough to "completely eradicate" Tenrou Island and imprint a giant crater into the ocean.
Flight: Being a Dragon, Acnologia possesses the ability to fly, using his large wings to travel great distances, maneuver high up in the air, and perform aerial assaults on those below him.
Immense Durability: Acnologia is capable of shrugging off attacks from very powerful Mages, such as Erza Scarlet, Laxus Dreyar and Mirajane Strauss. Even attacks from Natsu Dragneel, Gajeel Redfox, and Wendy Marvell, who all employ Dragon Slayer Magic, the Magic that is renowned for its legendary ability to slay Dragons, had absolutely no effect on Acnologia. Not even attacks from Dragons can harm Acnologia as shown with the Black Dragon taking the full force of Igneel's massive fire breath attack and emerged unscathed as if nothing happened.
Immense Strength: Given his immense size, Acnologia is easily capable of reducing a substantially-sized area to rubble by simply landing on top of it. As a testament to his immense strength, Acnologia can engage in a head-on physical confrontation with Makarov in his Titan form and easily gain the upper hand. According to Gildarts Clive, despite the amazing feats Acnologia performed on Tenrou Island, the Dragon wasn't using the same level of strength as he was during their brief confrontation. Rather, Gildarts noted that the Black Dragon was toying around with every last one of them.
- (To Igneel) "I recognize you as my enemy, Dragon. And I shall slay you." 
Battles & Events
|Five Dragon Gods||Aldoron • Ignia • Mercphobia • Selene • Viernes|
|Deceased||Acnologia • Acnologia (Dragon) • Animus • Atlas Flame • Belserion • Dark Dragon • Grandeeney • Igneel • Irene Belserion • Levia • Metalicana • Motherglare • Rock Dragon • Scissor Runner • Skiadrum • Weisslogia • Zirconis • Zirconis (Spirit)|
|First Generation||Acnologia • Gajeel Redfox • Irene Belserion • Natsu Dragneel • Wendy Marvell|
|Second Generation||Erik • God Serena • Laxus Dreyar|
|Third Generation||Future Rogue Cheney • Rogue Cheney • Sting Eucliffe|
|Fourth Generation||Quartum Army|
|Fifth Generation||Black Dragon Slayer Knights • Georg Reizen • Kiria • Madmole • Nebaru • Skullion Raider • Reiss|
|Deceased||Acnologia • Future Rogue Cheney • God Serena • Irene Belserion • Reiss|