Zeref Dragneel

Zeref (ゼレフ, Zerefu) is considered the strongest and most malignant Mage in Fairy Tail, who possesses incredibly deadly and powerful magic. He currently appears as a self-hating, reclusive youth who cannot control his power.

Appearance
Despite being hundreds of years old, Zeref has the appearance of a young man. He wears high-collared red (black in the anime) and tan robes with gold trim, along with a large, flowing white toga draped around his torso. He has short black hair, dark eyes, and abnormally sharp canines. He also wears a circle-shaped necklace.

When angered, Zeref's irises become red and gain a black ring around the pupil, giving him a much more menacing appearance.

Personality
Zeref is said to have been the darkest, most evil Mage in the history of the Magic World, mastering the Black Arts and creating many Demons, some of which still wreak havoc in the present.

In the modern era, Zeref seeks to isolate himself and is very calm, sincere, and conflicted. He wishes to die to atone for all the sins he has committed, and may commit in the future. He shows concern for others when he warns them not to come near him, knowing that they would die if they did. He is also somewhat emotionally fragile, as when he realizes that Natsu is not ready to kill him yet, he breaks down in tears. Zeref often kills with no prior incentive or knowledge.

In spite of all this, Zeref is very vindictive, and will punish those who he believes to be evil. This was shown when he ruthlessly killed Hades, whom he thinks has committed a number of unforgivable sins. As a result of his immortal life, Zeref has developed a misanthropic loathing for humanity and its repeated idiosyncrasies of hatred, evil, and conflict.

History
During an undisclosed era, Zeref witnessed the deaths of individuals in a great war, having also been cursed at some point he began peculating others souls nearby with lack of intentions.

It is stated he is from ancient times and presumably wields unfathomable power from which even the most timbultuous of mages quiver at. The mage Ultear Milkovich comments on a legend of how he journeyed to an ancient land, mastered and assimilated Dark Magic and brought into existence tens upon thousands of demonic forces which brought the world under disorder.

At some point of time, Zeref learned the value of life and because of this he was not able to use his powers like he used to. This caused the power of Zeref to be considerably less threatening then it was once. However, if Zeref happens to forget the value of life again, there will come the time when the full extent of his power will be released. Zeref felt guilty after this and did not want to kill anymore. So, he stayed in Tenrou island, cut off from humanity.

Tenrou Island arc
On Tenrou island, Zeref lays peacefully, asleep, on the ground. When night descends, he is attacked by a pack of wolves. Their efforts to kill the Dark Mage are, however, in vain, as he releases a wave of Death Magic, killing not only the wolves, but much of the surrounding ecosystem. Zeref then apologizes and wallows in misery, wishing to meet Natsu soon. Later, Carla has a vision, and sees that Zeref will somehow be involved in the S-Class Mage Promotion Trial. During the trial, he runs into Elfman and Evergreen and warns them to stay away from him, as his Magic is beginning to run rampant. However, when the wave is released, Natsu arrives and saves his fellow comrades from the deathly black wave. Zeref is then shocked to see Natsu, saying that he has "grown", but Natsu says that he doesn't recognize the Dark Mage. When he tells the Fairy Tail Mages that he has been expecting Natsu's arrival, Natsu misinterprets the statement as a declaration of challenge and rushes towards Zeref, landing a fierce blow to his face. Zeref is unfazed by the punch and stands up, disappointed that Natsu is not ready to kill him, causing him to shed tears of frustration. Zeref then unintentionally releases another wave of Death Magic, but Natsu's scarf absorbs the blast, saving the lives of everyone present. Zeref then proceeds to make his escape, however, Grimoire Heart is now aware of his presence, and seeks to hunt him down. Zeref then rests next to a tree and claims that the world continues to reject him, before crying once more. Later, Zeref is stated to be in a "state of slumber". Shortly thereafter, the battle between Fairy Tail and Grimoire Heart. At the end of the war, an enraged Zeref sneaks aboard the Grimoire Heart airship and confronts the remainder of the Seven Kin of Purgatory, including their Guild Master, Hades, about the horror they have brought upon the world. While there, Zeref reveals that he was never "asleep", but, rather, he was always "awake". He also reveals that when he understands the weight of human life, his cursed body will eliminate his surroundings; but when he forgets about it, he is able to fully control his Death Magic. He blames Grimoire Heart for the summoning of Acnologia, claiming that it will now end the current era. He then tells the group to repent for their unforgivable sins and casts Death Pillar on Hades. The power of the spell causes huge damage to the airship and slays Hades, sending him plummeting to the sea. Zeref then senses something and wonders if it's Acnologia. As the airship continues to fly onward, Zeref witnesses Acnologia destroying Tenrou Island and shuts his eyes, stating, tearfully, that Natsu's journey has ended.

Grand Magic Games arc
Zeref is stated to still be at large, with the Magic Council trying, unsuccessfully, to track him down. As Fairy Tail celebrates their victory in the Grand Magic Games after returning to Magnolia, Zeref sits, deep in thought, in the nearby forest; Obra runs up his shoulder. Zeref then senses Mavis Vermilion behind him and states that even though he cannot see nor hear her, he can sense her presence. With a smile on his face, Zeref repeats Mavis' statement that they were close to one another seven years ago, and answers that he has decided on where he is going to die when she asks him so. Zeref states that he's lived for centuries and has seen the rise and fall of different ages, and that he's seen the cycle of hatred continue on and give rise to new evil and conflict between people, but adds he's looking forward to the new age that will end all this. With his attitude growing more solemn by the minute, Zeref looks down and asks Mavis how many times people have repeated the mistakes of the past, but is told that despite that, humans will continue to live on. Zeref, however, counters this statement by explaining that if humans continue to repeat mistakes, then they aren't really living and that he is no longer anything that man can come to love. Now removing himself from the ground, Zeref tells Mavis that he has reached a conclusion about humanity: if the world continues to reject him, then he shall reject the world; Mavis tells him that Fairy Tail will be its salvation. Bowing his head, the Black Wizard tells the deceased Guild Master this will be his gift to humanity, thereby allowing them to start anew. Zeref then tells Mavis that he will not start a war but, rather, will simply cause a one-sided annihilation of humanity of which no human soul will survive, earning him a glare from Mavis, who tells him that Fairy Tail will be the one who will stop him, and he will be the one to be destroyed. Destroying the forest with his Death Magic, Zeref smiles and internally concludes that his and Natsu's final battle is drawing near.

Tartarus arc
Zeref later appears at Tartarus' headquarters. As Natsu is cleaning out the troops of Tartarus, his enemies are suddenly stopped in midair and Natsu finds himself standing in front of Zeref. The Dark Mage smiles, noting that he expected Natsu to come this far and then states that Tartarus is Zeref's bookshelf: where all of his "books" reside. Zeref continues by explaining that he wasn't the one to establish Tartarus, but rather, it is a guild made by the Demons that he created, namely their master, E.N.D. Natsu catches on to the name of the Demon, noting it to be the one that Igneel wanted to kill, but Zeref corrects him, stating that the Dragon couldn't do so. Natsu then takes out the Heat Blade, claiming that he will be the one to defeat E.N.D. to inherit his father's will. However, his attack is deflected by the aura surrounding Zeref, cutting the blade in half. Zeref then encourages Natsu, however, he also warns him that E.N.D. is the strongest Demon he created and that he, too, will face the decision of whether to let the Demon live or to kill it. The Dark Mage gets ready to leave, leading Natsu to protest. Zeref explains that he cannot show himself in front of Tartarus as they have gone through so much trouble to find him; just appearing would be a "kill-joy". Bidding farewell, Zeref notes that only Natsu or E.N.D. will be able to reach him, vanishing shortly afterwards.

Some time later, he retrieved the book of E.N.D. right out of Gray's hand, while the Ice mage and Natsu were arguing about destroying E.N.D., claiming that it is very important to him. Zeref praised Mard Geer for his attempt to revive E.N.D. But when Mard states that he can realize what the Dark Mage wished for, Zeref turned Mard into a book and burns it. Zeref then tells Natsu that he wanted to finish their fight today, but can't since Acnologia was in the way. Before vanishing with the book of E.N.D. in his hand, he warns Natsu that if he can survive this desperate situation, he will give him even more despair. Later, in a dark room, Zeref remarks that Natsu has to try and overtake him, calling the Dragon Slayer "Etherious Natsu Dragneel."