Ansem, Seeker of Darkness

"All worlds begin in darkness, and all so end. The heart is no different. Darkness sprouts within it, grows, consumes it. Such is its nature. In the end, every heart returns to the darkness whence it came. You see, darkness is the heart's true essence."

- Ansem talking to Sora about the darkness.

"Behold the endless abyss! Within lies the heart of all worlds: Kingdom Hearts! Look as hard as you are able. You'll not find even the smallest glimmer of light! From those dark depths are all hearts born! Even yours. Darkness conquers all worlds!"

- Ansem reveals Kingdom Hearts.

Ansem, Seeker of Darkness (also known as Xehanort's Heartless) is a major antagonist from the Kingdom Hearts franchise, appearing as the main antagonist in Kingdom Hearts and Riku's story in Kingdom Hearts: Chain of Memories, and one of the supporting antagonists in Kingdom Hearts 3D: Dream Drop Distance. He is the one of the alternate forms of Master Xehanort.

Creation

 * See: Master Xehanort and Terra-Xehanort

Ansem the Wise started to research the Heartless with an apprentice named Xehanort, who is actually the body of Terra converted into an amnesic vessel by Master Xehanort. When Ansem decided to stop his research, Xehanort continued it with the aid of Ansem's other apprentices, including Braig, Xehanort's accomplice. Eventually, the apprentices fell so deep into darkness that they all became Heartless, though their bodies remained as Nobodies thanks to their strong wills. In Xehanort's case, his Heartless took on Ansem's name, while his Nobody called himself Xemnas.

Wearing robes to conceal his lack of a body, "Ansem" traveled back in time to meet a teenage Xehanort and orchestrated the young man's destiny as part of his previous incarnation's plans. Returning to his time, "Ansem" oversees Maleficent gathering the Princesses of Heart as part of his plan to find Kingdom Hearts and engulf all worlds in darkness.

Kingdom Hearts
Ansem first appears to Sora prior to the Destiny Islands' destruction. Though he does not properly introduce himself at the time, Ansem makes a cryptic message to Sora regarding the fate of the Islands. During the Islands' destruction, Ansem appears to Riku and opens a Corridor of Darkness, sending the boy to Hollow Bastion.

Later, once Maleficent has almost completed gathering the princesses, Ansem possesses Riku's body. He acquires a Keyblade forged from the hearts of the princesses sans Kairi's and uses it to corrupt Maleficent, turning her into a dragon, but she is slain by Sora and company.

Sora then travels to the Final Keyhole, where Ansem awaits. Ansem explains that Kairi's heart is really within Sora and reveals his true identity before attempting to use his Keyblade to draw out Kairi's heart. Sora duels with Ansem, emerging triumphant, and prepares to seal the incomplete Keyhole. As Kairi is still comatose, Sora is forced to use Ansem's Keyblade to save her at the cost of the Keyhole's completion and his own transformation into a Heartless, and subsequently, the births of the Nobodies Roxas and Namine.

Ansem, having expelled Riku's heart and remodeled the boy's body, reappears and declares that Kairi's part is done. He tries to kill her, Donald, and Goofy, but Riku's heart stalls Ansem to buy the heroes time to escape. Ansem retreats to the End of the World, with a restored Sora in pursuit.

In a final battle, Ansem declares darkness is the source of all power, believing that Sora is still ignorant of the truth. Sora, though, retorts that Kingdom Hearts is light and destroys Ansem's physical form with the Door to Darkness.

Kingdom Hearts: Chain of Memories, Kingdom Hearts: 358/2 Days, and Kingdom Hearts II
Despite his physical form's death, a fragment of Ansem remains in Riku's body and tries to tempt Riku into falling back into the darkness when the youth emerges in Castle Oblivion's basement. However, seeing that Riku has accepted darkness and not him, Ansem becomes frustrated with Riku and is defeated in battle. However, Ansem points how that he'll take Riku's body when the time comes. Eventually, while fighting Roxas six months later to help the resting Sora, Riku is forced to tap into Ansem's powers and adopts his form in the process.

While Riku helps him from the shadows, Sora learns "Ansem"'s true identity as the Heartless of the real Ansem's apprentice, Xehanort. It was only while aiding Sora in the Castle that Never Was that Riku was purged of "Ansem"'s influence and returned to normal.

Kingdom Hearts 3D: Dream Drop Distance
Due to Young Xehanort's travels through time, "Ansem" is among the versions of Xehanort summoned and made a member of the True Organization XIII. "Ansem" taunts Riku throughout his journey through the Sleeping Worlds until Riku defeats him and escapes into the real world to thwart the real Organization XIII.

Quotes
"I've come to see the door to this world."

- Ansem talking to Sora on Destiny Islands.

"This world has been connected. Tied to the darkness...soon to be completely eclipsed."

- Ansem discussing the Destiny Islands.

"You do not yet know what lies beyond the door."

- Ansem when Sora asks where he came from.

"There is so very much to learn. You understand so little."

- Ansem when Sora notes he's from another world.

"A meaningless effort. One who knows nothing can understand nothing."

- Ansem before disappearing.

"Know this. The heart that is strong and true shall win the Keyblade."

- Ansem talking to Riku.

"For that instant, it was. However, you can become stronger. You showed no fear in stepping through the door to darkness. It held no terror for you. Plunge deeper into the darkness, and your heart will grow even stronger."

- Ansem talking to Riku.

"It's really quite simple. Open yourself to the darkness. That is all. Let your heart, your being, become darkness itself."

- Ansem before he gives Riku power over darkness.

"Yes... A Keyblade. But unlike yours, this one has the power to unlock people's hearts. Allow me to demonstrate. Behold!"

- Ansem stabbing Maleficent.

"Now, open your heart, surrender it to the darkness! Become darkness itself!"

- Ansem transforming Maleficent.

"The Heartless were using Maleficent from the beginning. She failed to notice the darkness in her heart eating away at her. A fitting end for such a fool."

- Ansem upon Maleficent's defeat.

"Don't you see yet? The princess's heart is responding. It has been there all along. Kairi's heart rests within you!"

- Ansem revealing the whereabouts of Kairi's heart to Sora.

"It is I, Ansem, the seeker of darkness."

- Ansem revealing his true identity.

"So, I shall release you now, Princess. Complete the Keyhole with your power. Open the door, lead me into everlasting darkness!"

- Ansem before he attacks Sora.

"So, you have awakened at last, Princess. The Keyhole is now complete. You have served your purpose. But now it's over."

- Ansem when showing himself to Kairi, Donald and Goofy.

"Take a look at this tiny place. To the heart seeking freedom this island is a prison surrounded by water. And so this boy sought to escape from his prison. He sought a way to cross over into other worlds. And he opened his heart to darkness."

- Ansem revealing his true form on the remnants of Destiny Islands.

"So, you have come this far and still you understand nothing. Every light must fade, every heart return to darkness!"

- Ansem before battling Sora.

"It is futile. The Keyblade alone cannot seal the door to darkness. Kingdom Hearts! Fill me with the power of darkness..."

- Ansem after the World of Chaos has been defeated.

"Supreme darkness..."

- Ansem when Kingdom Hearts starts spurring darkness.

"Light? Bu-but why...?"

- Ansem before his death.

"Why do you shun the dark?"

- Ansem talking to Riku.

"Stop resisting. Accept the darkness. You have no choice... if you are to serve me again!"

- Xemnas before appearing before Riku.

"Clever boy. I knew you'd be the one to most appropriately serve me. And now, surrender to me again---"

- Ansem provoking Riku to attack him.

"You are weak. You need darkness. Surrender. Bow to darkness. Bow to me."

- Ansem trying to get Riku to give in to the darkness.

"You think that feeble little light can save you from the darkness that I command? You shall feel my dark powers---in your bones!"

- Ansem before battling Riku.

"This is a card crafted from your memory. Advance through the world it creates and soon, you will understand... Chasing after light is not the way. It will not give you distance from the darkness. There is no running from the darkness."

- Ansem after giving Riku some cards.

"To use it or not is your choice. I'll be waiting, Riku... for you to sense it and yield to the darkness in your heart!"

- Ansem before departing.

"More like a model. He is an example of what you should try to be. He accepts the darkness... just like you once couldn't help but accept me. But now you are afraid. Perhaps YOU are the one who is being fake. Fake when you pretend to have no fear"

- Xemnas discussing Riku's replica.

"Inside of the card-worlds... you grappled desperately with the darkness. Desperation is fear. You fight the darkness because it is what frightens you."

- Ansem talking about Riku's fear.

"You called out my name. You have been thinking about me...You're afraid of the darkness I command. Good...The more you think of me, the closer my return draws. And when I have awoken, I will take hold..."

- Ansem preparing to control Riku once more.

"Meddlesome king!"

- Ansem angered at Mickey's interference.

"You have let in the darkness, Riku. That means very soon your heart shall become an all-consuming darkness."

- Ansem talking to Riku about his darkness.

"The deeper the darkness runs inside you, the stronger I become. Controlling you is effortless."

- Ansem talking to Riku about his darkness.

"Why in such a hurry? I'll be here at the very heart of darkness...Watching you plunge into the same darkness---inside of you."

- Ansem after Riku enters the last basement.

"I have watched you fight. I know your strength. Your skill with darkness has grown. It has become more mature. And yet, why... Why do you accept the darkness---but still refuse me? You know you and I are similar. We both follow where the darkness leads. Indeed, we are the same, so why? Does some part of your heart still have a fear of the dark?"

- Ansem talking to Riku about his darkness.

"Very well. In that case... You shall sink into the abyss!"

- Ansem before battling Riku again.

"This... is hardly... the end... Your darkness---I gave it... all to you... My dark shadow... lingers... Someday... Someday... I will return!"

- Ansem before vanishing.

"So sad, the cost of yielding to the darkness."

- Ansem confronting Riku at La Cite des Cloches.

"But I embrace the darkness. And unless you hurry up and learn to do the same, your story will end just like his."

- Ansem threatening Riku before leaving.

"That is right. Sora can no longer wake up, no matter how many nightmares you consume. You cannot wake someone who has fallen into the chasm of dreams."

- Ansem.

"Dreams hold our memories. Sleep holds our dreams. And darkness—it holds our sleep. Sora's heart belong the darkness now."

- Ansem.

"But you feel it, don't you? This world, the nightmare, the abyss. Why haven't you returned to the reality whence you came?"

- Ansem.

"Dream of a dream. A two fold nightmare. This whole journey, you have been inside Sora's dreams. And now darkness within darkness awaits you."

- Ansem.

"At the start of your test, when you struck out from that tiny island, you saw me there dressed in a robe. Immediately you knew something was wrong. So without even knowing it, you dove into Sora's dream. And you became exactly what that sigil on your back represents: a Dream Eater to protect Sora from nightmares."

- Ansem explaining what Riku has become.

"After all your efforts to command the darkness and protect those you cherish, it is a shame you locked that power away in the end."

- Ansem.

"So you understand what to do. Set the darkness in you free, and you can rescue your friend."

- Ansem.

"At last, you see clearly."

- Ansem.

"That is your answer?"

- Ansem.

"You can try!"

- Ansem before battling Riku.

"Ever the fool, boy. And forever a pawn of the darkness!"

- Ansem before merging with his Guardian for a final duel with Riku.

"Come, guardian!"

- Ansem shielding himself with his Guardian.

"You insolent little...!"

- Ansem before entering "submission" phase.

"Submit!"

- Ansem ordering the Guardian to possess Sora.

"Come, open your heart."

- Ansem using the energy shield.

"My strength returns."

- Ansem powering up for Dark Shadow.

"What do you hope to accomplish?"

- Ansem using Dark Shadow.

"Do not deny your fear!"

- Ansem when using Dark Shadow.

"The final darkness is nigh!"

- Ansem finishing Dark Shadow.

"Take this!"

- Ansem using Dark Rush.

"Return to darkness!"

- Ansem spinning his dual-bladed Soul Eater.

"Welcome the darkness into your heart."

- Ansem summoning laser orbs.

"All shall be extinguished."

- Ansem summoning laser orbs.

"Still confused? Then perhaps this will enlighten you!"

- Ansem summoning laser orbs.

"Come forth!"

- Ansem summoning Bit Snipers.

"Come... Darkness!"

- Ansem using energy vacuum during the final phase.

"Now, you weak-hearted fools, witness real power!"

- Ansem using energy vacuum during the final phase.

"Is this the answer? It can't be!"

- Ansem upon defeat.

"Why do you refuse the darkness?"

- Ansem upon defeat.

"Is that all you've got?"

- Ansem during the first battle.

"You can't protect anything."

- Ansem during the first battle.

"Drown in Darkness."

- Ansem during the first battle.

"Protect me!"

- Ansem shielding himself with his Guardian during the first battle.

"Accept the Darkness."

- Ansem during the second battle.

"Feel the Darkness."

- Ansem during the second battle.

"Now show me what your precious "light" can do."

- Ansem.

Trivia

 * Ansem is voiced by Richard Epcar in the English version, and by Akio Ōtsuka in the Japanese version. In the first game's English dub, he was voiced by Billy Zane, who also played Cal Hockley in Titanic.
 * Zane would later play Commander Sam William Marshall, the main antagonist of the 2006 Turkish film Valley of the Wolves: Iraq, which became controversial because it depicted Americans as terrorists. Disney decided that since Zane was involved, they didn't want him involved in Kingdom Hearts, hence why Ansem has been voiced by Richard Epcar from Kingdom Hearts II onward.
 * When possessing Riku, Ansem's voice is blended in with David Gallagher in English and Mamoru Miyano in Japanese.
 * As a consequence of Richard Epcar replacing Billy Zane, all flashbacks of Kingdom Hearts in Kingdom Hearts II were subsequently redubbed with Epcar as Ansem.
 * Ansem's character model was altered in Dream Drop Distance to better match up with Xehanort's other incarnations and subsequently reused for HD 1.5 ReMIX.
 * Coincidentally, the name "Ansem" is an anagram of the word "names", reflecting how the name has been used by multiple characters, including Ansem the Wise, Xehanort and his Heartless and Nobody, and Riku. It could also reference how "Ansem" is not his real name, but rather an alias used to conceal his identity as Xehanort.