Power creep is very real in anime. Characters who struggle to win fistfights at the beginning of a series can be punching holes in planets by the end. With an endless supply of stronger enemies to fight, it's little wonder that characters have to transform into terrifying new forms to keep up.
Some transformation states make more sense than others, and some final forms caught fans totally by surprise. Whether because the final form is a hard contrast to the character's original form or because the final transformation is just plain bizarre, these forms stick out in viewers' minds as some of the most unexpected of all time.
Given that final forms inevitably appear near the end of important stories, there are spoilers below
8 Zeke Yeager (Attack On Titan)
Zeke Yeager's transformation into the Beast Titan is surprising in a number of ways. Not only does its hulking, hairy form stand in stark contrast to Zeke's more mild-mannered human self, but the Beast Titan's calm intelligence is also a massive contrast to the instinctual idiocy of most other Titans, instantly setting him apart from other Attack on Titan characters.
With its devastating throws, Titan control, and ability to transform Subjects of Ymir into Titans, the Beast Titan is an exceptional threat to everyone who stands in its way. There's no guessing, especially early in Attack on Titan, that a character like Zeke would be capable of such atrocities, which is part of what makes his transformation into the gargantuan ape so shocking. Zeke's true nature and motives are part of one of the most shocking anime betrayals, making this final form surprising in more ways than one.
7 Agumon and Gabumon (Digimon Adventure Tri)
Creature-collecting anime are known for their transformations since transformations are a huge part of what incentivizes trainers to collect, train, and battle these beloved monsters in the first place. Few series do transformations better than Digimon Adventure Tri, but there's still one final form that stands out among the rest.
The Holy Knight Digimon, Omnimon Merciful Mode, is unexpected not only because this form combines the mega evolutions of every Digidestined on the team but also because of how dramatically different this form is from Agumon and Gabumon. Seeing this Digimon obliterate enemies with its shining sword is even more of a treat knowing how cute and innocent it started out.
6 Sosuke Aizen (Bleach)
A series as long-running as Bleach is bound to have several characters with great final transformations, but arguably none in this series are as shocking as Aizen's. When Sosuke Aizen is introduced, it's easy to mistake this Captain of the Gotei 13 for the gentle thinker that he pretends to be.
Black-masked, toothy, and sporting energy-shooting skulls on his wings, Aizen's Hogyoku form is a terror on the battlefield. One doesn't get to be a Captain in Bleach without power and talent, of course, but even with that expectation Aizen's final form sets itself apart from his comrades both visually and in sheer power.
5 Garlic Jr. (Dragon Ball)
Where does one begin with Garlic Jr.? Likely one of the most despised villains in the entire Dragon Ball franchise, this pint-sized antagonist first appears in Dragon Ball Z: Dead Zone and returns in The Garlic Jr. Saga. In his normal form, he's small, green, and has a protruding tooth, none of which exactly screams "imposing,"
Then Garlic Jr. transforms into his final form which is absurdly muscular, even by the muscle-bound standards of Dragon Ball. Seeing the miniature menace transform into someone so grotesquely muscular is disconcerting, to say the least, and for fans who already struggled to get on board with a tiny green tyrant named after a vegetable, Garlic Jr.'s final form was one step too far.
4 Tsuru Tsurulia III (Bobobo-bo Bo-bobo)
Nothing about Bobobo-bo Bo-bobo is serious, which should be evident from its title. As wrestling games know, including a strange cast is one way to entice an audience, which is perhaps how Bobobo-bo Bo-bobo arrived at Tsuru Tsurulina III, aka Czar Baldy Bald III, emperor of the Margarita Empire and show's main antagonist.
After Tsuru absorbs Don Patch and Bo-bobo he transforms into his final form: a purple, buck-toothed, angel-winged freak of nature that's as disturbing as it is hilarious. None of this is to say that he isn't dangerous: Tsuru is one of the show's most powerful characters in his final form, but the contrast between it and his over-the-top but decidedly human normal form is a little much.
3 Toguro (Yu Yu Hakusho)
Younger Toguro possesses the ability to regulate what percentage of his power he releases, dialing his strength up from 0 to 100%. At 100%, his muscles and skeleton expand and contort, making him far larger than before and comically buff. He's no slouch in this form, though, as both his strength and speed go through the roof.
Having final forms be conditional is a popular anime trope, but even by anime's standards the requirement for maintaining 100% Toguro is rather extreme: he must consume the souls of living beings or lose his power. Final forms and dramatic transformations were nothing new when Yu Yu Hakusho premiered, but 100% Toguro's muscle mutant look was a shocking contrast to the sleek and graceful final forms of his contemporaries.
2 Over (Bobobo-bo Bo-bobo)
Bobobo-bo Bo-bobo can't help but top itself when it comes to surprising final forms, which at least in part makes up for having such a confusing title. Over is an imposing character with a strange quirk: he has six lights on his chest, and the angrier he becomes, the more lights light up. When the last light turns on, Over transforms into his final form: Torpedo Girl.
Considering Over has one of the most unnaturally chiseled chins in all anime, his transformation into a blushing, eye-lash batting, anthropomorphic warhead is more than a bit unexpected. Maintaining the trend of similar villains, Torpedo Girl is not someone to take lightly in terms of power, regardless of the absurd appearance.
1 Magikarp (Pokemon)
Pokemon has too many iconic transformations to count, and while the transition from cute Charmander to awe-inspiring Charizard may stick out in fans' minds, no transformation subverts expectations quite like that of Magikarp into Gyarados.
Magikarp is the butt of every joke in the Pokemon world, a useless water-type famous for his useless Splash move. There is nothing impressive or dangerous about this glorified goldfish. When pushed, however, Magikarp transforms into Gyarados, a terror-inducing sea monster who strikes fear into the hearts of sailors and Pokemon alike. Unlike other characters who started out powerful and only became more so with their transformations, Magikarp started at the bottom and climbed close to the very top.