Acnologia

"Fear? As if I would be like one of the demons of Zeref's books? Don't make me laugh! I am the king of dragons, Acnologia!"

- Acnologia to Igneel

"What do you want, Black Wizard?"

- Acnologia to Zeref.

Acnologia (アクノロギア Akunorogia), also known and fearsomely reputed as "The Black Dragon" in the Book of Apocalypse, is a puissant Dragon and an enemy of humanity. He is the secondary main antagonist of Anime/Manga series Fairy Tail.

Appearance
Acnologia is a mastodonic dragon whose entire upper body, is covered in black, round scales, which in turn are decorated by spiraling, blue markings. Its lower body, specifically its belly, inner tail and legs, is grey in color, and seems to be rather smooth. It possesses a blunt, rounded head with four large and elongated plates extending backwards, and has white beady eyes. Its mouth is full of sharp teeth, and below it is an elongated protrusion pointing downwards. Acnologia’s gargantuan, multi-layered wings are composed of the very same plates covering its whole body, which take on a formation reminiscent of a bird’s feathers. Its massive tail splits in two at its end, where the black plates disappear, and takes on a double stinger-like appearance. In his human form despite being 400 years old has the appearance of a muscular young man with long dark blue colored hair. His eyes have black circles around them and he bears the same light blue markings as he does in his dragon form. For attire he dons a high collared black cloak and has a necklace of red dragon claws around his neck and a sash around his waist. He bares a gold ring on his arm and baggy pants that are decorated the same as the former article of clothing.

Personality
While other Dragons appear somewhat amicable to humans, Acnologia is inimical towards them, and perspectively scrutinizes them as infinitesimal. Zeref words it, "it sees them as nothing more than insects pestering him". 400 hundred years ago Acnologia was a ruthless,bloodthirsty, and a violent person. In his dragon form he shown to be very destructive and violent as described in legend. Acnologia also has a love for battle against opponents who can challenge his own power and strength. In his human form Acnologia has a stoic and composed personality even after slicing God Serena's abdomen open he is still composed.

History
Prior to the beginning of the series, he was born as a human over 400 years ago. He was originally one of the first Dragon Slayers during the Dragon Civil War to support the coexistence of both humans and dragons. Unfortunately, Acnologia and other Dragon Slayers turned against their own dragons, killed them, and bathe in their blood. Originally believed to be done from the aid of Zeref, Acnologia physically turns into a dragon, and proclaimed himself to be the Dragon King. This event was forever etched into history as the Festival of the Dragon King.

For many years, Acnologia was feared by the people of Earth Land, as he was credited with the single-handed destruction of an entire country. At some point of time, Acnologia ran into Gildarts Clive when the 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, though Gildarts managed to survive, albeit with difficulty.

Tenrou Island Arc
Acnologia comes to Tenrou Island, wreaks havoc on it, and fights the Fairy Tail members on the island. In the battle, it causes so much devastation that Makarov is forced to hold him off to allow the other Fairy Tail Mages to escape. As the two fight, Acnologia is eventually able to knock Makarov to the ground. Just as it is about to kill Makarov, all of Fairy Tail comes back and starts attacking the dragon. Acnologia then flies into the air, and seemingly destroys Tenrou Island, and all the Fairy Tail members on it with his Dragon's Roar.

After these events, Acnologia takes back up to the skies and disappears from sight.

Tartarus arc
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.

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.

Avatar arc
One year after losing his arm to Igneel, Acnologia accepts Zeref's proposal to meet, and does so at an undisclosed rocky terrain, albeit in his human form instead of as a Dragon; Acnologia questions what Zeref wants, however he is met with inquisition, as Zeref points out that Acnologia could rule the world with his power if he wished, calling his motives unfathomable, though Acnologia also says the same of Zeref's motives. Acnologia then listens as Zeref tells him that he will not join or fight against him; rather, he will kill him along with everyone else in the world and fathoms that Acnologia has been waiting for someone to give him a true challenge and states that he will gladly take on the role of that challenger. Acnologia then gives a sly grin as Zeref tells him to wait for the ultimate clash between human, Dragon and immortal to approach.

Alvarez Empire arc
Still residing in the cave where he and Zeref conversed last, Acnologia mentions that where his stolen arm was hurts; adding that he will destroy everything at the Dragon King Festival, he gets up and takes on his Dragon form, after which he shouts that he is the true "Dragon King". As he proclaims his supremacy, however, a shadow-like substance extends from where his left arm used to be.

Acnologia, in his human form once again, later appears at the eastern war-front, just outside the borders of Bosco. There, he stands before three Shields of Spriggan—Jacob Lessio, August and God Serena—the latter having just ended his battle against the remaining Gods of Ishgar, as well as Jura Neekis. Claiming that he can quite clearly smell the stench of a Dragon, Acnologia challenges God Serena, with the Shield of Spriggan seemingly over the moon about finally encountering the "Dragon King". Before God Serena can finish his rant about how difficult it had been to find him, Acnologia suddenly attacks, tearing a hole in the side of his stomach with a single swift swipe of his hand. As the surrounding Mages watch on in awe, Acnologia proceeds to casually walk away from the scene, leaving the collapsed body of God Serena behind. As he takes his leave, he states that there are still seven more Dragon Slayers left, indicating that he intends to annihilate each and every one of them, until all remnants of the Dragons have been wiped out of existence.

Powers and Abilities
Dragon Slayer Magic: As one of the first people to learn Dragon Slayer Magic he is one of the first Dragon Slayers. Over time however he slayed many dragons and became a Dragon himself due to the overuse of his lost magic but retain the ability to change back into his human form. While it is unknown what element he employs in his casting of dragon slayer magic, it grants him the ability to reap the souls of dragons leaving them in a half dead state.

Dragon Transformation: Acnologia contrary to the legends around him did not entirely become a dragon and has the ability to enter and exit his Dragon form at free will.

Dragon Roar: As all dragons and Dragon Slayers, Acnologia can perform a breath attack of its element. It is unknown what such element is, but once it's fired in the form of a giant beam it is capable of causing a huge explosion, which was enough create a gigantic crater in the water.

Flight: Being a dragon, Acnologia possesses the ability to fly, using its large wings to travel over long distances, manoeuvre high up in the air and perform aerial assaults on those below it.

Immense Durability: Acnologia was shown capable of shrugging off all the attacks from the Fairy Tail members who came to Makarov's aid. Even those from Mirajane in her Satan Soul form and the ones from three different Dragon Slayers, whose Magic is supposed and thought to be able to harm dragons, were utterly useless against it.

Immense Strength: Given its gargantuan size, Acnologia is capable of easily reducing a wide area into rubbles simply by landing on it after flying high up into the sky, and to engage in a physical confrontation with Makarov in his Titan form, injuring him in the process and eventually gaining the upper hand. Despite easily dominating the various Fairy Tail members, many of which possessing S-Class abilities, on Tenrou Island, Gildarts claimed that Acnologia was not using the same level of power it did back during their past confrontation, and that it seemed like it was just playing around with them. Even in his human form he holds tremendous raw strength as shown when he slayed God Serena the infamous strongest Mage in Ishgar with a single bare hand ripping through his abdomen.

Immense Speed: Only in his human form he is shown to move at blinding speeds.

Major Battles

 * Fairy Tail vs. Acnologia
 * Igneel vs. Acnologia