Xemnas is the leader of Organization XIII, and is fought as a boss in Kingdom Hearts Final Mix, Kingdom Hearts II and Kingdom Hearts 3D: Dream Drop Distance. In Kingdom Hearts Final Mix he challenges Sora at the Hollow Bastion, while in Kingdom Hearts II he fights Sora at both Memory's Contortion and within Kingdom Hearts itself, and in Kingdom Hearts 3D: Dream Drop Distance, he is the final boss of Sora's story, battling him in the World That Never Was in order to damage his heart.
Xemnas commands a gigantic, draconian battleship-like Nobody known as the "World of Nothingness" during several parts of his final battle with Sora and Riku. The dragon has a small main body, a long, segmented neck, and a round head with numerous tall, thin spikes lining it. Its mouth is somewhat beak-like and Xemnas, covered in armor, sits on a throne on the top of the head. The throne is adorned with large spikes and other additives that resemble the Nobody emblem, and large, seemingly organic, orange objects connect Xemnas to the battleship. The dragon's wings are thin, angular, and each is emblazoned with a black nobody symbol at the joint. Each wing also has several thin, black and white "feathers" with tips resembling the Nobody logo. Its thin arms end in three-fingered, segmented hands and each arm is lined by four blue diamond-shaped spikes of increasingly smaller size. In place of legs, the Dragon has two massive, conical engines with two smaller engines on either side of the main ones. It also has a long, thin tail with four conical objects connected to its tip. The World of Nothingness is predominantly colored in light shades of silver and metallic blue.
While commanding the dragon, Xemnas dons armor adorned with dozens of Nobody symbols. The shoulder pad on his left shoulder, helmet, crown, boots, knees, and breastplate all sport these designs. His crown and shoulder pad are gold, while the rest of the armor is colored in light shades of blue and silver. He has two silver belts on his waist and what seem to be white feathers on his right shoulder in place of armor. Several cords criss-cross in front of his torso, connecting to massive, oblong pieces of armor worn on each arm. Xemnas's faceplate is beak-like in structure and he wears clawed, metal gloves. He also wears black pants underneath the armor. Perhaps the most striking features of this armor are the oddly-shaped "sleeves" that are attached to each of Xemnas's arms. They are a mixture of red, orange, yellow, and white. He also wears a massive, similarly-colored cape that seems to connect him to the dragon. This armored form, referred to as the Armored Controller, bears a striking resemblance to No Heart.
In his final section of his battle with Sora and Riku, Xemnas's appearance is unchanged, save for his cloak. His once all black cloak is now a white one covered in black designs, many of which resemble the Nobody logo.
The Armored Controller's name reflects the armor Xemnas wears and his command over the World of Nothingness.
Early concepts for the Xemnas battle included two gargantuan Nobodies in place of the World of Nothingness, formed from Dark City rather than the Castle That Never Was: King (キング Kingu ), which had a vaguely humanoid upper body adorned in Nobody sigils and wore an immense crown, and Kentauros' (ケンタロウス Kentarousu ), which resembled a dilapidated version of the King attached to a quadrupedal lower body, with the crown becoming a spiked ruff.
 Kingdom Hearts Final Mix
At the start of this battle, immediately Lock-On and summon Tinker Bell and prepare any form of Aero you have (preferably as a shortcut). This will minimize the damage Xemnas can do to Sora. He will immediately execute an energy-ball attack, the balls exploding into orb-like, damaging force fields. While it is advised that the player has their most powerful abilities equipped, they must be careful at close range, as Xemnas will counter with a damaging shield technique or a powerful slashing combo. As the player must also be wary of their MP, Elixirs and Megalixirs are strongly recommended.
After about three quarters of Xemnas's pink HP Bar have been depleted, the hooded Nobody will begin to teleport around the battlefield, ultimately increasing his speed. Escape his energy ball or slash/shield attack by keeping track of the dark cloud that surrounds him. Once Xemnas hits his orange HP Bar, however, battle difficulty increases even further. Xemnas will summon a ring of blue Ethereal Blades in the air before him, the blades firing at Sora when Xemnas gives the command. This technique can be avoided through the use of Dodge Roll. When his yellow bar is almost completely depleted, Xemnas shrouds the field in darkness, surrounding himself with energy. Long-range lasers will then fire from him in all directions. Remain close to Xemnas to avoid as much damage as possible. Another option of escape is to use the Glide tactic.
From this point forward, Xemnas's most basic attacks gain more strength, the Nobody now summoning a ring of red blades rather than blue. The effect of this attack is still the same, but damage is increased. Xemnas's final and most dangerous tactic is an HP-draining attack, messing up Sora's commands, replacing them with "Shock" and "Release" (かいほう, kaihou). If Shock is chosen, additional damage is caused to Sora, and the player must wait for Release to appear within the command box and select it just right to halt the attack and return to normal condition. The light from the command may be rather bright, so Sora should be away from Xemnas as often as possible when dealing with such an attack inflicted on him before he resumes his focus and offense. Once Sora's HP hits zero, Tinker Bell will revive him. As she can only be used once, the player now must rely even more on his Curaga spell. So long as the player heals periodically and follows strategy options mentioned above, Xemnas will be eventually defeated.
Xemnas also proves more difficult than Sephiroth due to not flinching and spamming his attacks relentlessly, and thus for advanced strategy, the player can try the Magic Gravity in this battle because if it hits while the player is locked on to Xemnas, he won't move or release any attack for a short time as he gets stunned, and Sora will receive Tech Points, so Xemnas can be attacked but be ready to use Dodge Roll to avoid his counter attack. The safe way to do this is attack him exactly three hits after Gravity hits him then Dodge Roll and repeat Gravity. Also, one must learn to cast the spell on him at the right time, as Xemnas during an attack he pulls off might have a chance of shaking the spell off, thus, even though Tech Points are gained, there is a chance he will retaliate hard if you're not careful.
Note that Xemnas will only flinch to air combos, so keep that in mind when moving in to attack him, especially if stunned. Equipping the Gravity Break ability also works well but to make things better, and Zantetsuken works fine as well in stunning him for Tech Points, as well as being able to somewhat hit him through his teleporting. Be sure to remove any Combo Plus abilities to access the combo finishers sooner before the battle, enabling you to attack with higher chances of not being interrupted. Prepare Curaga just in case the player needs healing. With good timing, it is also possible to slide past or underneath the energy balls he fires with the Sliding Dash. Should that connect, remember to combo from that to use a ground combo finisher if needed.
 Kingdom Hearts II
 First Battle
When the battle begins, Xemnas will ensnare Sora in a field of energy that will slowly drain his health, then teleport to the top of Memory Skyscraper. Sora must rush to the bottom of the building and use the Reaction Command "Facedown" to break the energy field and charge up after Xemnas. Xemnas will leap down to confront Sora as he nears the top. At this point, one of three Reaction Commands appear depending on how close Sora is to Xemnas. The first is "Clash", where they pass each other harmlessly. The second is "Breakthrough", where Sora attacks Xemnas with a single attack. At the last second, the command changes to "Finish", where Sora attacks Xemnas several times and hits him into the side of the skyscraper. You are recommended to hit the Triangle button at "Finish". Note, however, that not hitting Xemnas will cause him to deal damage to Sora.
After the sequence ends, Xemnas will begin his normal attack pattern. He will teleport in an orb of darkness frequently, emerging to attack Sora rapidly with his Ethereal Blades, spinning, flipping and kicking to attack from all sides. These attacks can be blocked with Guard, or more easily, Reflect. Xemnas will also project a barrier, blocking Sora's attacks and knocking him back. He can be stunned, so Sora can easily connect combos. However, Xemnas tends to teleport away right afterwards, or if Sora attacks him too many times, he will teleport away in the middle of the combo.
Later in the fight, Xemnas will repeat the opening sequence involving Sora running up Memory Skyscraper. The Reaction Commands for the second time are the same as the first. Once he gets weaker, Xemnas teleports more often and more quickly than before. Overall, Xemnas is not an overly difficult boss, and can be hit with combos with ease. He can be defeated easily as long as the player heals when needed and has some healing items as back-up.
 Replica Data
In his respective data battle in Kingdom Hearts II Final Mix, Xemnas doesn't start off the battle with the HP drain move. Using the "Finish" command on Xemnas while facing him on Memory Skyscraper at the end of the battle leaves him stunned at the bottom of the building with a single HP left, similar to the final battle. Merely repeat tactics used in the fight against the true Xemnas, and he shall fall. This is only the first portion of the battle, Sora then forced to challenge Xemnas's final form with Riku as a Party Member.
 Energy Core
The final battle with Xemnas begins. The player must make sure that he or she has saved the game before entering the battle, as this option will not be available again, and there is no turning back. As soon as the battle starts, Xemnas begins to bombard Sora with buildings. Use the Reaction Command to avoid damage, and then pass through the doorway before you into the next area. Run forward and use the "Skyscraper" command to reach Xemnas's massive Dragon Ship. The player must now knock several Bomb Bell B Nobodies into the power generators of the ship. The player must use "Stunt Dodge" to dodge both the generator's laser attack and explosion upon destruction.
Sora then finds himself in the main core of the ship. Attack the core, dodging aerial attacks from the ship's "claws" and the lesser Nobodies that spawn once the core surrounds itself with a protective barrier. It should be noted that only by destroying the Nobodies does the core become open to attack once again. Use the "Proceed" Reaction Command to enter the next phase of the battle.
 Armored Controller
After destroying the main core of the Dragon Ship, Sora is faced with an armored Xemnas. The Nobody will use a massive sword to deal damage, having a long range. Not only does Xemnas have access to this attack, but those of past defeated Organization members, as well. He can summon Demyx's Water Forms, which can deal great damage, but give much-needed HP Balls upon defeat. Xigbar's Sharpshooters may fire lasers while a ring of fire and Axel's Eternal Flames appear on the ground. Xaldin's lances will cause wind damage, Saïx's Lunatic able to knock Sora back in a powerful shockwave. Xemnas may also select Luxord's Fair Game to damage Sora, too. Merely dodge these relatively weak attacks, and show Xemnas no mercy. Drive Forms can be used for only this portion of the battle, and greatly increase the rate at which Xemnas's HP is depleted. Heal periodically. It should be noted that should the player fall, King Mickey is available to revive Sora, even though he and Kairi were locked outside of the door. Xemnas is also stationary during this battle.
After the fall of the massive Dragon Ship at Sora and Riku's hand, it rejuvenates and teleports the two Keyblade wielders to an alternate dimension. The fly to the head of the ship, where they find the stationary, armored Xemnas awaiting them yet again. The Nobody will attack with a long-range sword swipe as in the last battle, dealing a lot of damage on contact. After one bar of HP is depleted, Xemnas will slam his weapon against the floor, sending Sora and Riku flying, as well as dealing very mild damage.
Xemnas will bombard Sora with lasers and buildings, so the player must use the Reaction Commands to get back to the ship. Failure to do so will result in Xemnas blowing Sora away and dealing minor damage. Once this is done, immediately and repetitively use Aerial Dodge (smash the O button) in order to dodge Xemnas's next tactic, one that allows him to summon snow-flake shaped energy that fires lasers with no hope of escape. Should this not be done, the player can attempt Aerial Dodge again, or merely allow damage and then let themselves fall to the point where they can safely glide back to the ship.
After Xemnas's second HP Bar is depleted, these lasers will continue to fire as you grapple with Xemnas. Be aware that he may summon a damaging shield, just as he did in his previous battles. Regardless of his Drive Form levels, Sora has full access to each Form's ability, allowing easier movement and dodging. Riku will also heal Sora with Cure Potion if his HP falls below critical.
 Xemnas (Dragon Form)
This fight pits Sora and Riku in a Gummi-Ship-style battle against a massive Dragon Ship, which is piloted by Xemnas. Only three commands are available on the menu: Attack, Drain, and Shoot. Use Drain when enemy ships fire lasers at you, filling the Charge Gauge. If you fill this gauge, the Triangle Button can be used to fire a powerful Reaction Command, "Mega-Laser". This attack will, if not completely, drain large portions of the ship's HP without fail. If Bomb Bells appear near Sora, he can press the Square Button to fire lasers to deal damage, but the Attack option would offer higher accuracy. Shoot should only be used against enemies that are far out of range. All enemies that bombard the ship via Shoot deal massive damage.
Sora must first tackle the Dragon Ship's tail. Utilizing a combo of the commands mentioned above, this should hardly be a challenge. Xemnas may fire a large array of missiles, however, and since Sora cannot heal in this battle, the player should dodge by flying in circles to each corner of the screen.
After destroying the tail, Sora must defeat the "legs" of the ship. Mega-Laser will come in handy here, and the player can also fly in circles to dodge the snowflake-shaped lasers that are fired. After defeating both of these limbs, Sora can proceed to the wings.
Before the first wing can be destroyed, Xemnas will fire "snowflake lasers" as well as missiles. Both tactics can be dodged via flying to each screen corner. Once this is done, the command process repeats itself yet again. Defeat both wings in order to clear the battle and progress.
 Final Form
Xemnas will first throw Sora and Riku into the air, leading to a series of aerial slash attacks and round-house kicks. It is possible however, to avoid being thrown in the air if the player has Reflega in his magic shortcut menu and uses it immediately after the battle begins. These tactics can be dodged by using the "Reversal" Reaction Command. If the player wishes to deal minor damage to Xemnas as he teleports around, the player can manually select the Trinity Limit ability. This approach would then lead to the "Block" Reaction Command. It is also possible for a cinematic to play where Xemnas knocks Sora's Keyblade away. At this time, the player should activate the Reaction Command Defend, where Riku tosses Sora's Keyblade back to him and they both force Xemnas away (doesn't deal damage by the way).
Eventually Xemnas will allow Sora and Riku to drop down. He will then teleport around the battle area, shooting threads of dark energy that can be dodged via Reversal. When Xemnas reappears, he uses a clone in an attempt to trick the player. Attacking the wrong Xemnas will result in the true Nobody slashing with his Ethereal Blades or dealing a devastating round-house kick.
As his HP depletes, Xemnas will shoot energy balls that explode to both block and cause damage. When it depletes even further, he begins to teleport rapidly, encircling Sora and Riku with lasers. He and his clone may then appear together or separately to shoot at Sora. These moves can be avoided via Reflega or Guard, and if the player is willing to be wasteful while possibly dealing damage, a Limit. Once these tactics are completed, Xemnas will trap Sora, slowly draining his HP and forcing the player to take on the role of Riku, who only can jump, cast Dark Aura, and attack. While Xemnas drains Sora, his clone will attack Riku with energy balls, slashes, and even the damaging shield tactic. The clone can be annoying, but Dark Aura will stun him just a little. Use this time to run to the real Xemnas and Sora, using Dark Aura every three steps until you get to the true Xemnas. Jump to him and execute the Reaction Command in order to free Sora, stunning Xemnas. This leaves the Nobody boss open to great amounts of damage.
Xemnas will then repeat the throwing technique used at the battle's start, repeating his normal attack pattern as well. Just before Xemnas's HP hits zero, he then fills the battlefield with lasers, shrouding the area in darkness. The player must now repeatedly mash and in order to keep Sora and Riku alive. Failure to do so will spell certain death. Once the area is cleared of lasers, brief cinematics are shown, eventually reducing Xemnas's HP to 1. Simply start a Limit or deal a combo finisher to finish off Xemnas.
It should be noted that Riku will heal Sora when his HP is low. Items still should be brought into battle, as it is best to be hit by Xemnas's drain attack with a full bar of HP. Ethers are also good for restoring much-needed MP. It should also be noted that while Xemnas's final attack brings him to 1 HP, the player can deplete his HP to 1 before the attack is executed, as well. Riku cannot die in this battle, because he is needed for the entire battle. The only time that Riku can die is when Xemnas starts to drain Sora's HP.
 Replica Data
The battle with Xemnas's Final Form Replica Data is the same as the original, save for a few differences, the obvious one being that he has more health. After that the battle plays out the same, the only other difference is that Xemnas can use his "Invitation to Nothingness" attack multiple times, so healing often is a must. To that end, equip many Elixirs and Potions. Also, have the Cure spell in your shortcuts. Just follow these tips, and the ones above and Xemnas should fall with ease.
 Kingdom Hearts 3D: Dream Drop Distance
At the start of the battle, carefully time Slide Rolls to avoid the massive buildings Xemnas hurls at Sora. Aside from his daunting number of HP bars, the only thing he has that a player of any level should need to worry about is his speed. Because Xemnas constantly travels around the battlefield in a sphere of darkness that moves much faster than Sora can (and also makes him immune to any type of damage), it is important that the player Lock-On to him as soon as possible so he can never catch Sora off-guard. As soon as Xemnas reappears from the dark sphere, press to guard against the ensuing Ethereal Blade combo or round-house kick. This will hault Xemnas's attack on the spot and leave him open to Sora's Counter Rush, which should serve as his main source of offense instead of major commands.
Should Xemnas surround Sora with lasers, leap over them with High Jump and use the Air Slide/Sonic Impact/Double Impact combo towards the opposite end of the battlefield to avoid them. When Xemnas traps Sora in a cage comprised of his damaging energy shields, simply High Jump over them and repeat the Air Slide/Sonic Impact/Double Impact combo to avoid the ensuing barrage of lasers. If the player wishes to take a risk, he or she may leap out of the cage and attempt a Flowmotion attack. Xemnas may try to defend himself with a single energy shield from time to time, but Sora merely needs to stay away from it to avoid taking damage.
After half of his HP has been depleted, Xemnas resets the battlefield, necessitating Sora to time Slide Rolls an dodge the incoming buildings. When Sora gets close to Xemnas, the Nobody hurls another building at him that knocks Sora into a dive. When Xemnas throws another building at Sora, watch for the Reality Shift icon to appear on it and immediately trigger Nightmare's End. Successfully complete the mini-game by slashing the white links in the chains to destroy the building and reset the battlefield once again.
In the aftermath of this chain of events, the battlefield changes once again. Xemnas remains stationary at the end of the battlefield for a brief time, tired and huffing. This is Sora's time to unleash major commands such as Ars Arcanum now that he is not in danger of being sliced to ribbons by the boss's Ethereal Blades. Use Flowmotion to get to Xemnas, but be cautious not to attack from the final rail, or the boss will return to form instantly. After taking enough damage, Xemnas warps reality back to the former battlefield once again.
As his HP begins to dwindle, Xemnas increases the frequency and ferocity of his attacks. Resume the guard and Counter Rush combo strategy, and use a powerful Dual Link like Unison Rush to finish the boss off. It is advised that the player bring two Curaga commands into battle to ensure maximum healing potential and cancel out the wait for command reload time should his HP need replenishing. Use Flowmotion to Sora's advantage, and the battle should end with minimal difficulty. It is a necessity that the player enter this fight with a full Drop Gauge when at a lower level.
The Sidecar Glider used by Riku and Sora during the second fight against Xemnas's Dragon Form
 Notes and references