NOTE: This article is about the character called Darkness from the Kingdom Hearts series. For information about darkness as an abstract force of evil, see Darkness on The Evil Wiki.
Darkness is the name given to a group of dark entities that are the overarching antagonists of the Kingdom Hearts series. They appear as the main antagonists in Kingdom Hearts Union χ and minor, unseen antagonists in Kingdom Hearts III Re Mind.
A long time ago, Darkness possessed a physical form but shed it so it could defeat Light. At some point after, it watched over the Master of Masters while he was writing the Book of Prophecies based on the knowledge he received from the Gazing Eye placed in his No Name Keyblade and read all the passages he wrote, thus learning that Ventus, a Keyblade wielder from the future, would someday bear Darkness within him. Darkness also refers to the Master of Masters as an "old friend" since they had talked to each other at some point in the past, although they were unable to truly understand one another because of their opposing positions.
The Master of Masters reveals to Luxu that there are thirteen main Darknesses and that the most powerful of them were to be placed inside himself, Luxu and the Foretellers while the other six were to enter the bodies of the five Dandelion Union Leaders and the locked inside the data Daybreak Town respectively so they could be destroyed in the future by a person with a strong heart of light.
Kingdom Hearts Union χ
Before the Dandelions, a group of Keyblade wielders gathered by Master Ava to cross over to another worldline before the end of the world foretold in the Book of Prophecies, Darkness possesses one of them, Ventus, and fulfills his subconscious desire for power by killing Strelitzia, one of the new Union leaders, and stealing her Rulebook while using his body. After that, Darkness exited Ventus' body, shapeshifted into Master Ava, and makes him believe he's really a Union leader by giving him the rulebook stolen from Strelitzia, telling him to meet the other new Union leaders at the Keyblade Graveyard at the allotted time.
When the previous worldline's timeline about the Keyblade War was eventually rewritten after reliving the events of the past for two years, Maleficent goes forward in time and meets with Maleficent after she's tried and failed several times to undo her defeats at the hands of people such as the Player character and Prince Phillip by traveling to the past, explaining to her that it never worked because the Master of Masters knew in advance about her arriving from the future to try and alter the past, so he excluded Maleficent's homeworld, Enchanted Dominion, from the real world until after the Keyblade War ends, and the world Maleficent was in is merely a data replica of Enchanted Dominion. Darkness, fearing that Maleficent would return to the future with knowledge of the past, trapped her within Data Enchanted Dominion and ensured that the data of Radiant Garden would be excluded from it. Darkness then leads Maleficent to the data version of Daybreak Town and instructs her to use the lifeboat in the clocktower, the purpose of which is to allow one to cross worldlines; since the lifeboat was never finished, Maleficent could use it to move to a different time rather than a different world. Since the lifeboat being incomplete would cause her to lose her physical from upon being used, Maleficent would require someone with memories of her in the future in order to recreate her body, which she will inevitably find since she exists in the future according to the Book of Prohecies. When Maleficent questions Darkness about its identity, it responds by calling itself an "old friend" and explains to her that it needed her to return to her own time so she could be used as a waypoint for someone to allow someone to time-travel to the future.
When Maleficent finds the lifeboat, she hesitates to use it to return to her own time, which allows Lauriam (one of the Dandelions and Strelitzia's brother) to catch up with herself and Darkness, wherein Maleficent reveals the purpose of the lifeboat to Lauriam before attempting to use it to leave, but Lauriam doesn't intend on allowing her to escape, so he attacks the evil fairy, but Maleficent is able to defeat the Keyblade wielder with Darkness' help, and she uses the lifeboat to return to the real world. Upon her arrival, Darkness instructs Maleficent to use the lifeboat again to return to her own time, but refuses to come with her because it still has something it needs to do in the past.
Afterwards, Darkness returns to Data Daybreak Town and shows itself to the Union leaders after Ventus collapses as a result of a combination of his guilt over Strelitzia's death and Lauriam's anger at him for it. When the Union leaders question it on its intentions, it responds that it doesn't have any goal it's trying to achieve, to which Lauriam asks it why it killed Strelitzia. Darkness elaborates that Ventus had an unconscious desire for power, and it had helped him fulfill his desire by killing Strelitzia and having him take her place as a Union leader, meaning there wasn't actually any reason for Strelitzia's death. This enrages Lauriam and prompts him to attack Darkness, but is easily defeated by it due to his weakened state from his earlier battle against it and Maleficent. Then Brain questions Darkness regarding why it chose Ventus as its vessel and how it's related to the Master of Masters, and then summons his Keyblade and fights it alongside Ephemer and Skuld. However, Darkness still manages to defeat most of the Union leaders. At that point, Brain coaxes it into revealing what it's really after: "Infection," and it also clarifies that it's only fulfilling the role that the Book of Prophecies assigned to it, and that he was originally part of a hive mind of darkness that it used Ventus to separate itself from, thus gaining an identity of its own, uncaring of the sacrifice that was needed to do so. At that moment, the Player character arrives on the scene through a portal from Game Central Station, and they and the Union leaders stand up to fight Darkness again, but Darkness still remains confident that they would lose against it, and scoffs at Lauriam when he speaks of getting out of the data world, asking him and the other leaders how they would accomplish that. When told that they plan to use the lifeboat like Maleficent did, it ridicules them for being unaware of the lifeboat's true purpose and explains it to the Union leaders and Player, also explaining that due to Maleficent's departure using the lifeboat, the lockdown and destruction of the world's data has already begun. While Player and the Union leaders do manage to briefly defeat the dark entity, it is unable to be destroyed due to not having a physical body. When Darkness summons Darklings to attack Ventus, he awakens and uses the light within himself to destroy them, and then, aware that Darkness had used him to give itself a form, realizes that he could do the same to it, and he begins fighting it in order to turn it into something that can be destroyed.
It is unknown what exactly happened to Darkness after its fight with Ventus, but Lauriam implies that it may now be a part of Ventus.
Kingdom Hearts III Re Mind
At the beginning of Sora's journey to restore Kairi's heart using the power of waking after Master Xehanort shattered it, an entity referring to itself as "Darkness" stops him when he enters Ventus' heart. Sora questions if the entity is Vanitas since he also referred to himself as "darkness" before his demise during the Second Keyblade War, but it does not reply and instead transforms itself into a Pureblood Heartless called Dark Inferno χ to battle him. As this battle took place while the Second Keyblade War was occuring in the past as per future Sora's perspective, it is unknown if this entity is Vanitas after his demise or another of the thirteen Darkness entities.
True to its name, Darkness are featureless humanoid figures surrounded by a miasma of dark energy.
Mot a lot is known about Darkness in terms of personality, but according to the Master of Masters, it is an amoral being with no sense of reason whose thought processes are completely incomprehensible to humans, and vice versa. The only part of humans that it understands is their negative emotions, and it despises beings with hearts of light. It does not have any reason or remorse for the evil deeds it does, merely doing them because the Book of Prophecies says it's its role to.
Powers and abilities
Darkness has the power to hide inside of another living being to possess them and control their actions, as it did to Ventus to kill Strelitzia. It can shapeshift, as shown when it takes on the form of Master Ava. It can manifest itself as other dark entities, such as Heartless being that the latter's existence are devrived from it. It has the ability to turn itself invisible, allowing it to act discreetly, as well as teleport. In a fight, it can attack its foes with dark powers. It can summon Heartless through Dark Corridors to fight alongside it. As formless entities, it is immortal and immune to destruction in that state and can only be destroyed while inhabiting the physical body of other beings such as humans.