Bleach
- Winter War: Aizen's Hollowification experiments fuse shinigami with their zanpakuto, the results being tortured abominations who still retain awareness of their situation, but can't do anything about it.
Crossover
- Battle Moon Wars gives us the ninja RoSHIaKI, a fusion of Michael Roa Valdamjong and Tohno SHIKI (Roa's 18th incarnation, who is not the same person as the protagonist of Tsukihime).
- The Bridge (MLP):
- It's revealed the Big Bad Bagan is a permanent fusion of three super ancient kaiju named Doragon, Mizu, and Enjin, who did so to save the world long ago (before he eventually fell to evil). He can project clones of them to act as Avatars, but they are now mindless extensions of his will.
- While she goes by Mothra, Lea is more accurately a fusion of Mothra and Battra resulting from the Earth lacking the necessary mana to remake Battra after his death and instead merging his essence and power with Lea's egg to create a hybrid of both divine moths. According to Word of God, it is similar to the process that created Bagan, but unlike him she can still reproduce asexually and could theoretically create a new independent Mothra and Battra by doing so. The same applies to her Mirror Universe counterpart Battra Lea.
- The ROM hack Brutal Mario has the seven Koopalings merging together to fight Mario, a homage to the 7 Heroes from Romancing SaGa 2. It needs to be seen to be believed
. - Child of the Storm:
- The finale of the first book reveals that Lily Potter fused with the Phoenix after her presumed death, as part of a deal with the entity in question, becoming the White Phoenix of the Crown - the Phoenix's primary aspect. While this didn't strictly make the Phoenix more powerful, it did provide an overall focus that She usually lacks.
- In the sequel, Reynolds performs one of these with a hunger demon to become the Void.
- Dungeon Keeper Ami:
- Keepers have the ability to possess their minions. This gives the keeper access to skills and powers possessed by the minion in question.
- This gets taken one step farther with youma, whose appearance is determined in part due to their self-image. As a result, when possessed, they become literal amalgams of Mercury and whatever they looked like before.
- Taken yet further by Tiger, who possessed Mercury while she was also possessed by the Dark God Crowned Death. In that case, not only did Mercury and Tiger's features blend, but Mercury's armor fused with her/them. resulting in a towering, muscled amazon with metal skin and the burning Crown of Crowned Death.
- In Equestria: Across the Multiverse:
- The Crystal Gems appear in a Crossover universe, and as such their fusions appear. As Diamond Tiara is a Gem in this universe, she can also fuse, but struggles to learn how for much of the arc due to only very recently finding out she's actually a Magenta Diamond. She finally manages to with Silver Spoon after Discord turns her into a Pearl, becoming Grey Musgravite.
- A world where everyone is a robot also has a program where they combine into a larger robot. The Mane Six become Harmony.EX and the CMC become Crusader.EX.
- A universe where the natives can fuse like the Gems can is discovered, and the Fusion Dance spell soon becomes learned by other members of the Alliance.
- The Brotherhood of Tirek apparently captured a high dimensional Eldritch Abomination and fused with it and each other to form 10th Dimensional Tirek, who required the 10D Ponies to perform a Crisis Crossover to defeat. This was also the only way Tirek could transcend to the 10th Dimension, as his selfishness would prevent it from otherwise happening. The 10D Ponies are also technically fusions of countless versions of themselves, but each individual one is also a separate individual, and the process happened naturally rather than being forced like Tirek's.
- Inferior or Superior: Professor Wheeljack's academic specialty is the study of Pokemon fusion. He rushes off at one point to witness the fusion of a Charizard and a Clawitzer.
- Infinity Train: Seeker of Crocus: Specter and Easter learn that when they have a high trust level with one another, it allows Easter — who originally was a lightning bolt who struck Specter down and merged with them but are currently capable of having their own separate body — to fully fuse with Specter and become Harmonious Storm. Through the author notes, the co-author admits that she was watching Steven Universe clips while brainstorming ideas.
- Inky Future: Artemis, Orion, Iris, Axl, Ayane and Ethan perform a Gem-style fusion after being blended, to save X from Tartar, taking advantage of their mixed-together inky ooze state. The end result is named "Leviathan", and the author also admits he took direct inspiration from Steven Universe, though unlike that show, conversation of mass actually matters and thus the resulting fusion is not only over eight feet tall, they are very muscular and have large breasts and Hartman Hips, as all of that mass from six people needs to go somewhere.
- This is the main benefit of Emerald Ace, Ben Tennyson's Stand in JoJo's Alien Adventure. Alongside having an Ultimatrix of its own, it also has the ability to fuse with Ben if both are transformed.
- Mike Pines: With some help from Bill, Molten Freddy manages to fuse themselves with Mike during Weirdmageddon until the group returns to the Mystery Shack.
- In one chapter of Monsters In Paradise, a naive Mismagius triggers a fusion with Marisa Kirisame completely by accident. The end result has Marisa's face, hat and hair, but Mismagius' dress-like body. Whether Marisa gained any powers from the fusion or not isn't brought up, however.
- Mushroom Kingdom Fusion uses the Power Booster variant: The playable characters can gain forms representing popular characters that are not playable. For instance, Mario has a Mega Man form and a Master Chief form, and Luigi has a Protoman form and a Red Spartan form.
- A Pony Out of Place (My Little Pony: Friendship Is Magic & Pokémon): In Flames And Twilight, Flare and Nightmare Moon become Knightmare Nova after Flare puts on the Alicorn Amulet.
- In Universe Falls, Steven's ability to perform Fusion with humans extends to his friends Dipper and Mabel in addition to his canonical Fusion with Connie. There's a three-part mini-arc devoted to introducing not only "Stevonnie" (Steven + Connie), but also "Maven" (Steven + Mabel) and "Stepper" (Steven + Dipper). Later chapters introduce "tri-fusions" of Steven and two of his friends, like Dipevebel (Steven, Dipper, and Mabel) from "Three's A Crowd", Mabonnven (Steven, Mabel, and Connie) from "Theory of Weirdness", and Convenper (Steven, Connie, and Dipper) from "Crack the Whip".
- No Hidden Contracts, Taxes, or Fees has Spouxls G. Kaardton, a fusion between Rouxls Kaard and Spamton G. Spamton after Kris injected the LoadedDisk, which contained Spamton's consciousnesses, into Rouxls's body to save him from turning into stone.
- Godzilla Neo: Mothra and Battra were once a single entity called Gigamoth, but were separated thanks to Ghidorah. With the rise of Bagan, the two reunite and become the god-like bug once more.
- Queen of All Oni: Amongst the Anthropomorphic Personifications in Jade's mind, the Aspect Paranoia is apparently the result of Fear and Doubt being brought together by the remnants of Kaito's chi.
- The Ultimate Evil:
- When Shendu takes over the body of his Other, Valerie Payne, he warns her that this trope will happen to them if they remain in such a state for too long. Since Shendu and Valerie's spirits now have absolutely no metaphysical barriers between them, and since their souls as Others seek to join by their very nature, it'll soon become difficult to tell where one being begins and the other ends, and it'll eventually become nearly impossible to separate them.
- In a desperate attempt to escape the Netherworld, Hsi Wu attempts to forcibly perform one on Jade by using their connection as Others in The Stronger Evil.
- Stars, Eyes of Heaven: The Deep Blue Moon file reveals that the fake Captain Tenniele from Stardust Crusaders survived his fight against Jotaro by fusing with his Stand Deep Blue Moon. The result have left him has with the mind of an animals that lives to hunt its prey for sustenance.
- In the climax of Kingdom Hearts Ψ: The Seeker of Darkness, Sora creates the Ultima Drive Form by fusing with 19 of his friends.
- Ultimate Sleepwalker: Sleepwalker and his human host Rick Sheridan ended up becoming bonded with one another. Sleepwalker became trapped in Rick's mind and could only emerge when he fell asleep or unconscious. One notable occasion reversed the fusion and Rick's consciousness ended up in Sleepwalker's mind, which allowed them to temporarily return to Sleepwalker's home dimension, the Mindscape.
- Galatea: After successfully stealing the Ladybug and Black Cat Miraculous, Gabriel attempts to use its power to both undo his wife Emilie's coma and cure Nathalie of her sickness. Instead, the wish creates a new reality where the two are fused into a new woman named Emilie who started as his trusted assistant before marrying him.
- Dekiru: The Fusion Hero! gives Izuku a Quirk where he can absorb materials like metal into his body to take on their properties, but he can also fuse with other humans, creating whole new people with whole new Quirks.
- In the universe of Ask Twixie, Twilight never became an alicorn, so she and Cadance fused together in order to handle Tirek.
- In the climax of Cutie Mark Crusaders Dream Warriors, the CMC combine together in the dreamscape to finally defeat Feather Duster for good
- Inverted in Diaries of a Madman. The various races of pony were created when Discord literally split the alicorns into three.
- It's revealed that How Trixie (Somehow) Saved Hearth's Warming that the three Windigos from the story were actually each thousands of Windigos merged into one due to the abundance of hatred running rampant at the time causing their population to skyrocket. Leidr, while a mutant sapient Windigo, is capable of this fusion as well and does so with his two nonsapient heardmates to go One-Winged Angel.
- Pony POV Series:
- Several ponies are the result of a Shadow of Existence fusing with a pony to create a new being. For example Twilight is the result of Minty's Light of Existence merging with the Shadow of Existence of G1 Twilight, Rainbow Dash is G3 Rainbow Dash fused with Firefly's Shadow of Existence and so on. If a person's Light of Existence is the one the Shadow originally possessed (as their Light reincarnated while their Shadow went to Oblivion), they recreate the original soul such as Yearling and Puzzlemint's Shadow of Existence merging, which thanks to Pandora resulted in them also becoming the real Daring Do, and Lovestruck fusing with Cupid's Shadow of Existence to reconstitute his Concept. However, it's noted the two must be compatible, otherwise it will go very wrong. This is especially true of the Shadows of Concepts, as while the end result is never shown, it's universally stated to be a Fate Worse than Death and create something horrific.
- Nightmare Eclipse forcibly fused every Twilight with herself every time the "Groundhog Day" Loop that she'd trapped Discord in reset. Fittingly enough, when defeated, Eclipse was forcibly fused with Twilight, resulting in Amicitia coming into being. This is a complicated one, as while Amicitia has all of Eclipse's memories, the Eclipse persona was completely destroyed.
- Diamond Tiara's Nightmare, Nightmare Nhilis forcibly merges the Spirits of Dark Magic with herself in an attempt to destroy them along with herself, resulting in her One-Winged Angel transformation. Power Booster variant, as they have little influence on her outside of some Fighting from the Inside.
- Rarity, in order to stop Nightmare Nhilis without killing her (which by this point Diamond is trying hard to get them to do), has her soul sent inside her and merges with the Spirits of Dark Magic to both free them and completes them, letting them realize their actions were wrong. One of them, presumably the final one, the Spirit of Dark Magic based off Loneliness who Rarity merged everything she didn't give to one of the other spirits with, resembles Nightmare Rarity post merger.
- Seven Days in Sunny June: The human Octavia Melody is a chimera, having absorbed her twin in the womb. Needless to say, this fact greatly disturbs her.
- Sharing the Night: The ancient alicorns Luma and Vita merged into a single being, Solaria, the first solar alicorn, as an expression of their love for each other. This turned out to be a terrible idea; by merging into a single person, they also doomed themselves to a life of loneliness, as their merged self would perceive herself as one being with two sets of memories, carrying an undying love for people that she would never see or interact with again.
- The Three Sisters: Cocoon sacrifices herself to save both Rarity and her sister Pupa by fusing them into one entity.
- Bent Out Of Shape: Lewis and Arthur accidentally possess Vivi while trying to protect Lewis' little sisters. The three have equal control over the body and can use all of their elemental abilities in tandem; Mystery notes a possesser and the possessee having even control is extremely rare, especially when multiple spirits are involved.
- Flowers Surround Our Soul is a Character Blog set in an Alternate Universe where Arthur and Lewis both tumbled off the cliff in the cave; upon death, their souls ended up "mushed" together, putting them into one body with four eyes and features of both. They speak in sync unless disjointed, and it's brought up that their memories are also smudged together, to the point they can't make much sense of them.
- In Son of the Sannin, Kiba and Akamaru develop a variant of their usual combined transformation jutsu. Instead of turning into a giant, multiple-headed wolf, Akamaru instead turns Kiba into human-like werewolf, enhancing their physical attributes while being much easier to control. Tamaki does a similar thing with one of her cats, turning herself into a Cat Girl.
- Rise of the Minisukas: The Sixth Angel is a merge of original series' Gaghiel and Rebuild's unnamed Seventh Angel. Basically, Gaghiel is wearing him like it was a body armor.
- In the game, Shades could already possess people. Tower of Babel takes it up a notch: there is a way for them to fuse fully.
- We're Here Together is drabble series with the concept that fusion is a learnable technique in the show's world, one that Luffy introduces to his teammates. Fusion here has its limits, however, as Devil Fruit users can't fuse because their fusion will have more than one Devil Fruit power in their body, and it could kill them if they don't unfuse in time.
- Hours 'Verse:
- In As The Bells Toll, the cognitive effects of the Deepscape and Minato and Ryoji casting Miracle together give the Wild Cards enough power to fuse with their Personas for the climax of the battle.
- In The Other 25th Hours, all of the Thanatos Defensive Line are able to fuse with their Personas to battle Thanatos and Keres.
- In the final battle of Heir Apparent, not only does Maruki fuse with Adam Kadmon as in canon, but the Phantom Thieves fuse with their Personas as well.
- Pokémon Infinite Fusion: The entire premise of the game is focused precisely around combining existing Pokemon from the first five generations (along with select mons from the fifth, sixth, and seventh gens) with the aid of the DNA Splicer item from Pokémon Black 2 and White 2. Any two Pokémon can be combined into a new "Fusion Pokémon", inheriting the stats, moves and abilities of the chosen mons.
- In Pokémon Master
- Misty and her lost twin 'sister' Valdera merge together to form Mistaria, resolving Ashura's love interest problem.
- A powerbooster variant happens with Triverion, who happens to be three Eevelutions merged into a... multi-headed dragon thing. It also happens with Mikey's Eevee and Missingno.
- Ruby Stars: In "Beta Buddies", Steven and Connie Fuse into Stevonnie to combat a giant Corrupted worm. After they, Amethyst and Sadie cling to the worm while it burrows underground, Stevonnie and Amethyst in turn Fuse together to become "Smokonnie Quartz" to poof the worm before she can dig back up and attack them again.
- The True Final Boss in Something Else is a merger of the Evil Guy and Ballser.
- The protagonist of With This Ring gets stuck in an Unwinnable Training Simulation and forgets it's a simulation. As he watches his friends die, he gets desperate and unites with the Ophidian, embodiment of avarice, giving him the power of a Physical God but making him unable to feel emotions other than avarice. For its part, the Ophidian is happy to have a host capable of putting desires into perspective and prioritising between them.
