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Characters / Undertale - Mettaton

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Click here to see his EX form. 
Click here to see his NEO form. 
A robot celebrity built by Doctor Alphys whose metal body renders him completely invulnerable to attack. She recently added sophisticated anti-human, pro-murder weaponry to him. Which should go well.
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  • Acquired Situational Narcissism: In Mettaton’s old house next to Napstablook's, you can find his diaries, which shows that he was rather devoted to his friends in his old life, but then he met Alphys and almost forgot about his friends. Thankfully, he reaches out to them in the Golden Ending, and assembles a quartet with Napstablook, Shyren, and maybe Burgerpants.
  • Actually Pretty Funny: During the "quiz" section that introduces Mettaton, at one point Mettaton will ask you who Alphys has a crush on. Answering either Undyne or Asgore will work, but if you answer yourself, Mettaton will declare that while that answer is completely wrong (and Alphys will have an incredulous look on her face), Mettaton finds the arrogance of this answer to be so amusing that he still won't penalize you for it.
  • Affably Evil: He's still a lot more "entertainment robot" than "killer robot"; he treats you like an honored guest on his show, and he shows absolutely no malevolence towards monsters. Subverted; he doesn't hate humans in general either (he actually adores them), he just wants to kill you to stop a massive war.
  • Agent Peacock: Especially in his EX form, which has very pretty looks, a near-perpetually-flirtatious range of facial expressions, attacks implementing his pink stilettos and heart-shaped core, and the honor of being arguably the toughest pre-endgame boss. Even before it's introduced, he's vain, flamboyant, cross-dresses during the opera segment, and by all accounts has a fixation on the finer things in life while also demonstrating that he's clever, charming, and competent.
  • A.I. Is a Crapshoot: The long and short of it is, the "killer robot" thing was an act set up to make Alphys look cool, but then he decides to kill the protagonist anyway, to save the rest of the human species (and get famous above ground in the process). Ultimately... it's a subversion, because his intelligence isn't actually artificial.
  • Ambiguously Bi: His similarities to Alphys and his flamboyant glam rock demeanor imply this, but his sexuality is never confirmed either way.
  • Androids Are People, Too: Everyone treats Mettaton as a normal being. Justified, as Bratty and Catty reveal that Mettaton has a soul just like any other monster. In fact, creating a robot with a soul is how Alphys came to become Royal Scientist in the first place. Possibly subverted, as it is strongly implied (and potentially confirmed in his dialogue for the unused alarm clock app) that Mettaton is a ghost from the Blook family possessing a metal body.
  • Anti-Climax Boss: Invoked with the fight against Mettaon NEO in the No Mercy route in order to demonstrate the futility of the sort of level grinding that gets you into that route - after intense build-up, including his own unique theme song, he dies in one hit. He doesn't even have an attack pattern.
  • Anti-Villain: He is set-up to be a Noble Anti-Villain first, as he never tries to stab you with your back turned and you can't actually die from any of his segments, before he is revealed to be a Well-Intentioned Anti-Villain that wants to kill you to stop a massive war, and to make himself a celebrity on the surface. Also goes in hand with Villain In Name Only for first not being evil to begin with, and that him desiring to kill humans is far from the truth.
  • Arc Villain: He is this in the Hotlands section of the game, especially when he takes his kid gloves off and starts hiring other monsters before trying to kill you himself.
  • An Arm and a Leg: During his EX fight, Mettaton will eventually lose his limbs. This happens sooner if the player attacks his heart-shaped core. He gets better later, as seen in his cameo during the Asgore fight intervention and the true credits.
  • Arm Cannon: He gets a prominent one as Mettaton NEO on the No Mercy run. Not that he ever gets to use it.
  • Artificial Intelligence: Mettaton was built by Alphys, though he does apparently have his own soul. This is because he really isn’t a robot, but a ghost possessing a metal body.
  • As Himself: Though Mettaton appears in many In-Universe films and TV shows, no character names or even personas are even brought up- he's always simply playing himself.
  • Attention Whore: The number of shows he apparently runs and some potential NPC dialogue implies that he's almost literally always performing, and at the end of the Hotland section of the game, he drives Alphys' plan Off the Rails and attempts to steal the player's soul partly to get a bigger audience than he already has by taking his career to the surface.
  • Awesome, but Impractical: In-Universe, as he clearly likes his Mettaton EX form very much, but due to the form's "inefficient" power usage, he can't stay in the form for very long until his battery power conks out. He gets better by the end of the game after getting fixed by Alphys. It's still unknown if the power problem got fixed or not. Exaggerated for Mettaton NEO, who looks intimidating but whose defense is so poor that he dies in a single hit. In that form he never acts even if you deliberately waste time, so it's also possible that Mettaton NEO was just a bluff.
  • Bad "Bad Acting": Somewhat invoked. For the most part, he seems enthusiastic and competent, but after the tile puzzle, he's clearly sick of the charade and of Alphys botching her lines, and he seems to just stop trying altogether.
    Mettaton: (after getting shot by the protagonist) OOOH! OOOOOOOOH! YOU'VE DEFEATED ME!! HOW CAN THIS BE, YOU WERE STRONGER THAN I THOUGHT, ETC.
  • Bad Boss: Zig-zagged. Burgerpants affirms that he's terrible to him at least, doing stuff like punishing him by forcing him to listen to an album of songs all about berating him and telling him how bad he is at his work if he doesn't perform to Mettaton's standards. and if he becomes king of the Underground, anybody who doesn't like him just... disappears, with the implication that he's getting rid of any dissenters. However, see Benevolent Boss below.
  • Beauty Is Bad: Mettaton, despite looking like a calculator on a wheel, is considered gorgeous by much of the underground, and he is the antagonist of Hotland. Makes a bit more sense with his EX form. Eventually subverted, after his Character Development.
  • Benevolent A.I.: Mettaton is an unusual example; he's extremely vain and conceited, but at the same time, makes it clear that he cares about his employees and the other monsters (except Burgerpants, maybe). He's actually a subversion, as he's a ghost possessing a robotic body.
  • Benevolent Boss: Talking to a few of his other employees after killing him on a Neutral Run reveals that he was a rather kind and well-liked boss. Therefore, it seems he was only a nasty boss to Burgerpants, and even then, he might have distorted the truth a little bit.
  • Beta Outfit: Mettaton’s first calculator-like form.
  • Big Brother Instinct: He's very protective and supportive of Napstablook, his cousin. Them calling him during the Mettaton EX fight makes him lose the will to fight you.
  • Big Entrance: You hear large, pounding footsteps shaking everything in the room, and then Mettaton breaks in through the wall and starts a game show!
  • Big "YES!": Mettaton lets out several throughout the course of the game, along with a voiced one when he transforms into his EX form.
    "Ohhhhhh yessssssssss!!"
  • Bishōnen Line: His two alternate forms are basically a pair of glam rock stars.
  • The Caligula: He shows hints of this in some of the neutral endings where he becomes the ruler of the Underground. See Cult of Personality below.
  • CAPS LOCK: His speech is written in all capital letters, to give it a robotic feel. Once he changes form, his text appears normally. He still uses all-caps in some sentences, implying his previous No Indoor Voice was mostly affected. Like the skeleton bros., it contrasts with Napstablook's all lowercase letters.
  • Cat Smile: He pulls a few smug ones here and there in his EX form.
  • Chainsaw Good: He seems to enjoy them enough to feature them regularly in his cooking show.
  • Chef of Iron: Literally. Actually, it's unclear how good his cooking skills actually are, but he already made the cake ahead of time, and he's a skilled combatant (with or without a chainsaw).
  • Clipped-Wing Angel: In his normal, rectangular form, he's totally invulnerable to the player's attacks. Not so in his EX form, which can be damaged easily and has terrible battery life to boot. His No Mercy run form gets this even worse, being his hardest-to-reach form and met with a lot of self-hype, when literally all it can do to you is potentially die throwing you out of the No Mercy run.
  • Combat Sadomasochist: If you choose to fight him in a neutral run, every hit you land against him results in him saying "Yeah!" and pulling an....interesting face. Once you knock some of his limbs off, he stops doing this.
  • Combat Stilettos: His humanoid forms have some killer heels. One of his early attacks even attacks the player with them in the form of legs with heels that start/stop moving when the player shoots them.
  • Crapsaccharine World: How Papyrus describes the Underground in endings where Mettaton becomes ruler. See Cult of Personality below.
  • Cult of Personality: In some neutral endings. If Toriel and Undyne are both dead, he becomes ruler. Anyone who does not worship Mettaton "goes missing".
  • Custom Built Host: Mettaton is a performing robot built by Alphys, but is actually a ghost-like monster, implied to be a cousin to Napstablook and Mad Dummy, possessing a mechanical body Alphys built for them so they could live out their dreams of being a star to monster-kind.
  • Cut the Juice: During your final confrontation with him, Alphys calls to tell you about a switch on his back that will make him vulnerable if flipped. It's a subversion: the switch isn't an off switch, but makes Mettaton switch forms. The vulnerability is that the switch-activated form has much lower defenses than the initial one. Played straight in his peaceful defeat, where his EX form drains his batteries much faster and puts him out of action, although he's already made peace with the human before shutting down.
  • Dance Battler: He's constantly dancing and posing as Mettaton EX, and he frequently uses his legs (and a disco ball) to attack.
  • Deadpan Snarker: To a truly hilarious degree. He'll never let an opportunity to snark at Alphys' or the Protagonist's expense pass by him.
  • Declaration of Protection: Despite his self-absorbed nature, he cares a lot about his cousin, Napstablook, and his friend, Alphys. It is more explicit in the No Mercy run, where he states there are people he needs to protect.
  • Didn't Need Those Anyway!: Unless the player manages to defeat him very quickly, his EX form will lose its arms and legs during the battle.
  • Disney Death: Pacifist route only. Raising his ratings to a certain threshold will result in his battery becoming completely drained, temporary 'killing' him on the spot. Justified, since you didn't outright destroy his body, and since he's fused with it now, attacking him will actually kill him for real. After his peaceful defeat, his inactive body is on Alphys' worktable undergoing repairs, which are completed in the True Pacifist Ending.
  • Does This Remind You of Anything?: His efforts to become corporeal are highly reminiscent of transitioning. He even goes through a pronoun change — Undyne, his former neighbor, only calls him "they" when you call her from his house, Napstablook's house, or the farm, implying that "they," "them" and "their" were the pronouns he used before he was able to transition into a robotic body. In all forms of his robot body, however, he goes only by "he," "him," and "his." Since Mettaton disappeared without a trace and didn't keep in touch, there would be no way for Undyne to know about the pronoun change. Another possibility is that ghosts, being incorporeal, go by "they", "them", and "their" by default, since all ghosts in the game are referred to this way, and only begin to identify with a specific gender once they've inhabited a body.
  • Early-Bird Cameo: Papyrus' randomly generated maze puzzle machine is Mettaton; this is more noticeable on a second playthrough or if you go back to see that it's gone. This also changes the context of it "messing up"; it wasn't a technical error or a cosmic bout of bad luck, it was Mettaton screwing with Papyrus.
  • Eating Machine: Has a cooking show, even. Justified, he's actually a ghost.
  • Even the Guys Want Him: Oh, yes.note  Papyrus calls him his "favorite sexy rectangle," and remarks that he wishes he lived in Hotland so that he could meet him. This is after Papyrus mentions about three times before how glad he is he doesn't live there...
  • Evil Counterpart: Mettaton represents what Papyrus would be if he became a serious threat similar to Flowey and Mad Dummy before him, if his quest for glory implied betraying the people who love him and if his narcissism overshadowed his qualities. Both are campy, hammy and narcissistic characters who have dreams of glory, challenge you with deadly puzzles, are the emotional support of a more introverted characternote  and are more dangerous than they appear:
    • While Papyrus' puzzles are far from dangerous, Mettaton's ones are more deadly.
    • While you have to cross the peaceful Snowdin Town before reaching Papyrus, Mettaton traps you into the trapped-filled CORE where you have to fight countless mercenaries.
    • While the former puts his glory quest aside to befriend the Human Child, the latter wants to take their soul to leave the underground alone, ruining decades of effort and patience for his own benefit.
    • While Papyrus can be spared no matter the path you choose, Mettaton is the only monster who requires to be hit to win, even in a Pacifist run.
    • While you can befriend Papyrus no matter the path you choose and being in good terms with him matters to reach the best ending, it's impossible to interact with Mettaton between the end of his arc and the True Pacifist ending.
    • While both of them can potentially become the ruler of the Underground in Neutral endings and neither of them have political knowledge, they handle things differently. While Papyrus has Sans to do most of the work, he at least tries to support the monsters by cooking spaghetti for them. Mettaton, on the other hand, tries to handle everything personally and miserably fails, all by transforming the Underground into a Police State where every non-fan of his TV show mysteriously disappears.
  • Evil Gloating: Seems to enjoy doing this quite a bit.
  • Exact Words: Because you defuse all six of his lesser bombs, the Big Bomb will not go off in 2 minutes. It will go off in 2 seconds. Too bad Alphys already hacked it. Too bad it was not an actual bomb.
  • Face Death with Dignity: If you kill him on a Neutral path, he'll Go Out with a Smile, coolly (and dishonestly) saying Alphys can fix him and wishing the player luck, thanking them for giving him the chance to "perform" for them. Even when you one-shot him in a No Mercy run, he'll go out with a smirk and a dry one-liner (or mocking you, if you flubbed the requirements for a No Mercy run at the very last point where it's possible to do so). On the Pacifist path, he acknowledges that his EX form has a Fatal Flaw in its poor battery life (not that the batteries can't be replaced until Alphys fixes the problem off-screen later). He postpones his debut in the human world to remain a cultural icon in the underworld, thanks everyone for tuning in, and lets his battery life finally run out.
  • Fantastic Arousal: Flipping Mettaton's switch elicits a satisfied-sounding "Oh, yes", implying that doing so turned him on.
  • Foregone Victory: You cannot actually lose during his quiz; his penalty attack always inflicts half of your HP rounded down in damage and thus cannot actually kill you. You also cannot die to any of his subsequent challenges along the way to the MTT Resort; if you fail, either he does something that spares you at the last second (such as abruptly going to a commercial break) or Alphys steps in to save you. As it turns out, this is all because Alphys and Mettaton rigged the entire journey so that she can come off as a hero. Mettaton's EX form averts this trope, as by then he's gone against Alphys' plans and is trying to kill you for real. Played straight once more with Mettaton NEO, as he not only goes down in a single attack, but also doesn't even bother to attack you.
  • Foreshadowing:
    • During Papyrus' fight, he uses various MTT-brand beauty products.
    • If you turn on the TV in Papyrus' house, one of Mettaton's leitmotifs will play. Papyrus also has action figures shaped like "sexy robots."
    • If you date Undyne before Mettaton is officially introduced, she'll comment that one of Alphys' friends came over, and proceeded to do nothing but lie seductively on the piano and feed himself grapes.
    • Mettaton's own behavior during his show foreshadows that the show you're participating in is just a setup to make Alphys look good. For example, a human SOUL is obviously much too precious to be made into a cake, being necessary to escape the Underground. Mettaton also seems strangely apathetic about defeat.
  • Four-Fingered Hands: With White Gloves. Word Of God says he's confused over how many fingers humans usually have because all of his knowledge comes from media, including western cartoons. He actually has several gloves with different numbers of fingers.
  • From Nobody to Nightmare: In the King Mettaton ending. He starts off as a nameless snail farmer/wannabe star, has become the Underground's biggest celebrity by the time of the game, and player-created circumstances lead to him becoming a tyrannical king.
  • Glass Cannon: Mettaton Neo: 90 ATK. 9 DEF. He dies in one hit; if you failed the No Mercy requirements at the end of his battle, he even lampshades it as he dies by saying that Alphys should maybe have worked a bit more on his defenses. Subverted, as he doesn't even attack you, thus rendering his stats irrelevant.
  • Glory Hound: A very sympathetic version. Since he still gets a soul by killing you, he knows that he'll be able to get through the barrier and get fame in the human world as a hero. He does honestly want to help both species, and by helping his ratings, you get him to realize you're a worthy hero to stop the war yourself and people already appreciate him, so he allows you to go on in peace.
  • Golden Ending: The quickest way to end the battle is by getting the ratings over 12,500 before Mettaton's limbs fall off. This can be done by changing in and out of armors, eating Mettaton-branded food, and throwing him the Stick.note  Though even though his limbs don't fall off, he still appears as just a head and torso in the Overworld.
  • Good All Along: Although he acted as if he wanted to kill all humans at Alphys' request, he actually wants to save humanity... which means he has to kill you so Asgore won't get your soul.
  • Go Out with a Smile: No matter what the player does, the last they see of Mettaton is a smile including if they kill him.
  • Graceful Loser: In the neutral and pacifist routes, he takes his defeat remarkably well. In the pacifist route, he even has a bit of a So Proud of You moment.
  • Gratuitous English: His "OHHH YESS!" is always written in English in the Japanese translation of the game. Additionally, quite a bit of what he says is written in katakananote , which carries the same meaning.
  • Harmless Villain: During encounters with Mettaton, no matter how much you fail at his tasks (answer every quiz question wrong, stand still during the bomb defusing segment, etc.), it's impossible to lose to him, and he announces his defeat and goes on his way. This is a hint that it's all a charade planned by Alphys, and Mettaton's not supposed to harm you. Once he admits the truth to you, he isn't so harmless.
  • Hartman Hips: In his EX form. It's a little hard to see due to his starting pose standing with his legs far apart and his later poses moving quickly, but his hips are quite wide.
  • Haunted Technology: Entering the house next to Napstablook's reveals his backstory. He's a ghost — Napstablook's cousin, to be precise — who had dreams of making it big in show biz, and was given a robotic shell by Alphys.
  • Having a Blast: He loves using bombs against you, both in the newscaster segment and in battle.
  • Heart Drive: His heart-shaped core.
  • The Hedonist: From what we learn about him as a person, he takes full advantage of the level of lux and self-indulgence his role as a high-profile performer living the dream affords him.
    Undyne: I don't really like that guy. ...But I admire his lifestyle!
  • Heroic Sacrifice: In the No Mercy run, it's implied that part of his real reason for fighting you, even though he knows he can't win, is to allow Alphys and other monsters to escape.
  • He's Got Legs: Lampshaded in his EX form. Praising Mettaton's legs during the essay portion of his boss fight nets you a ratings bonus. And in the ending when he forms a band with Napstablook and Shyren, his legs are noticeably the only part of his body not covered up by the metal box he wears.
    "Who needs arms when you've got legs like these?"
  • Hidden Depths: Underneath Mettaton's massive ego, biting sarcasm, and extreme self-centered nature, there's a genuinely smart entertainer who really does love his fans with all his heart. (...SOUL?) Enough that he chooses to give up going to the surface so he can stay in the Underground with them. There's also a small moment in the True Pacifist epilogue that speaks volumes about what kind of guy Mettaton is. The lion-like monster that said Mettaton's wearing a dress made him feel like maybe he could wear one, too, now has a dress on... specifically, the very one Mettaton was wearing. Turns out, Mettaton gave it to him! He's also a pretty good boss, according to everyone at the MTT Resort (besides Burgerpants), and really does care about Alphys and Napstablook.
  • Hired Guns: He paid practically every monster in Hotland to take the human down.
  • Hour of Power: His EX form has inefficient battery consumption, meaning he'll eventually run out of power (and lose his limbs) if the fight drags on.
  • Hypocritical Humor:
    • If you swear during your essay response, he responds...
      "Oh my! This is supposed to be a family-friendly show. Now stand still while I murder you!"
    • And if you answer Toby instead:
      "What the hell is that? Sounds... sexy."
    • He'll also call the player character "conceited" if they claim Alphys has a crush on them.
  • Impossibly Graceful Giant: He's not exactly gigantic, but he's incredibly agile and graceful for a metallic robot.
  • In Touch with His Feminine Side: He has no problem whatsoever with wearing pink and high-heels, or crossdressing for the musical segment. He's also delighted that his EX form is beautiful. Makes sense, given his similarities to Glam Rock singers. His bedroom is also entirely a lurid shade of pink, covered in stars and posters, and contains a diary collection.
  • Incoming Ham: Every time he makes an entrance.
    "OHHHH YES!"
  • Interface Screw: A rare example of this being used to help the player. He's fought using the yellow SOUL Mode, which allows you to shoot down his incoming projectiles before they hit you. Most of his attacks would be unavoidable without it.
  • Intrigued by Humanity: He started a human fan club before he became Mettaton. He's shown to have an infatuation with humanity, as most of his entertainment is based on shows humans love and his EX form is the most humanoid being in the Underground. He only wants to kill the Child to prevent a war between humans and monsters.
  • It's All About Me: He's ridiculously egotistical and self-indulgent. If he becomes king, he makes the Underground into an Egopolis.
  • Jerk with a Heart of Gold: An arrogant, smugly antagonistic attention hound he may be, but he cares quite a bit about his cousin Napstablook, is good enough friends with Alphys to have initially agreed to his Killer Robot role in a scheme for her sake, and seems to genuinely appreciate how much his fans value him. Also, in the No Mercy route, he confronts you even though he knows he can't win, and implies that part of his real reason for fighting you is to protect Alphys.
  • Jobber: You encounter him several times, but in almost all cases he instantly folds when you disrupt his plans. His plans also go south regardless of if you put in any effort to stop them, either due to Mettaton deciding to spare you at the last second or Alphys hacking his death traps. This is because he literally is a jobber; Alphys set him up to rapidly try and kill the human only to always fail, making Alphys look like a hero. Once he ditches this prerogative, he proves that he can kill if he needs to.
  • Killer Robot: As called out by his cooking show, "Cooking With A Killer Robot". It's all an act. It actually turns into an outright inversion, since his goal after dropping the act is actually to take the human's soul in order to prevent the barrier from being broken and save the rest of humanity (and become a star on the surface).
  • Large Ham: Easily outperforms Papyrus and Undyne in this department. Then again, he is an entertainment robot...
  • Last of His Kind: In a sense, after his fans become really upset over his decision to leave, he then realises that humans already have stars and idols, while he's all the monsters have to look up to as a celebrity.
  • Leitmotif:
    • Mettaton has no less than three leitmotifs. "It's Showtime" (which can be heard long before you actually meet him) is his TV host theme, used for his intro cutscene, while the bassline can be heard during his cooking show. "Metal Crusher" is his killer robot theme, used in his battles and a short remix occurs before his final battle. "Oh! One True Love" is his music-hall theme which reappears as "For the Fans" when you spare him.
    • "Death by Glamour," his boss fight theme, draws from the former two. The opening and endings parts are heard in the opening of CORE, the "chorus" can be found in the "chorus" of his previous theme Metal Crusher, and the bridge can be heard in It's Showtime!, Live Report, and Death Report.
    • While he has "Power of 'NEO'" for his NEO form, it's really just a remix of "Battle Against a True Hero".
  • Lightning Bruiser: Bordering into Confusion Fu territory. Mettaton's battle style is unusual and based on being varied, fast, and flashy to entertain viewers first and foremost. Trying to both entertain and battle, he's a competent fighter.
  • Logical Weakness: Mettaton is originally a ghost monster, given a physical form by Alphys. As a ghost, he was incorporeal and thus immune to nearly all attacks. However, as Mettaton, he's as prone to death as any other corporeal monster.
  • Mad Bomber: In his 'Newscaster' scenario, he traps you in an area full of bombs disguised as several seemingly innocuous things, like a glass of water and a dog. In his EX form, many of his attacks involve bombs as well.
  • Mean Boss: When it comes to Burgerpants in any case, not so much towards his other employees. He made a whole album purely dedicated to telling Burgerpants how bad at his job he is.
  • Meaningful Name: His name may be a reference to Metatron, an angel whose name abbreviates to MTT and who was a human before being transformed into an archangel. Mettaton also ascended from humble origins to become something greater than his original form.
  • Mirror Boss: Notable for being the only boss that has a SOUL present during the fight itself. In a reversing of roles, you can attack it just like how bosses attack your SOUL.
  • Morality Chain: It's implied that Alphys is one of these to him, as shown in one of the Neutral endings. In particular, the Neutral ending where he becomes tyrant ruler of the Underground has him mention that he wanted Alphys to help him rule, only to discover that she went missing. It's heavily implied that, had Alphys not disappeared and possibly committed suicide, Mettaton would have become a much better leader due to her advice.
  • Mr. Fanservice: Mettaton EX certainly doesn't play down this sort of appeal. Ironically, his default rectangular form is considered this in-universe, being, in his own words, "more photogenic," and Burgerpants admits to purchasing (non-working) "kits" to make himself more rectangular.
  • Multiple-Choice Past: Depending on what route you took. In a Neutral/Pacifist run, he was made as the entertainment-type rectangular robot and upgraded to his EX form later. In a No Mercy run, he was created as an anti-human robot first, then given his rectangular form later when he was re-purposed as an entertainment robot. Of course, his speech in his No Mercy encounter could be baloney. He takes a noticeable pause when he describes his rectangular form as "more photogenic" and despite having a fierce and imposing-looking appearance, doesn't attack you at all. Also, why would his old form be called 'NEO' (new)?
  • Musical Spoiler: Mettaton NEO's battle is hyped up to all hell, receiving a pimped-out new form and crazy stats to deal with you. That is, before you one-shot him. But the fact that his theme, "Power of NEO", is only a thirty-second loop should tip some off that it's going to end quickly.
  • My God, What Have I Done?: If you Spare him, he receives a call from Napstablook and clearly feels guilty about leaving them behind. It happens again in the neutral ending variant where he becomes king of the Underground; with Alphys "missing," he expresses regret over how he treated her.
  • Nigh-Invulnerability: His rectangular form is described to be impervious to attack by the CHECK option, and the only way to defeat him is to flick his switch so he becomes Mettaton EX, which has low defense and a limited power supply. Despite this, he appears to be fazed when you attack him in the dungeon segment, which is actually foreshadowing that he was merely playing along the entire time, as he is immune to your later attacks before you flip his switch.
  • No Celebrities Were Harmed: In his EX form, he has a striking resemblance to Ziggy Stardust and Michael Jackson, and one could even argue he looks a little bit like Prince, especially during the Purple Rain era. Squint, and you might also be able to see Trent Reznor in the 90's.
  • No Name Given: Mettaton is a name adopted by him after becoming a robot. His original name is unknown, although Papyrus calls him "Happstablook, the happy ghost".
  • No, You: If you throw out an insult or cuss-word during the essay portion of his last battle, he throws it back in your face with "This essay is supposed to be describing me, not you."
  • Non-Lethal K.O.: When fighting his EX form, you can either kill him with the FIGHT command... or you can raise your ratings to a certain threshold, at which point he'll decide to stop fighting and, at the same time, run out of battery power and shut down.
  • Older than They Look: His bishounen form looks like he's in his early twenties. However, Napstablook indirectly confirms that the snail farm existed before 'their best customer' Toriel left. If Sans' implication that she has been gone a hundred years is correct, the ghost cousins are over a century old.
  • Oh, Crap!: Has a mild version of this when his limbs blow off during your fight. He tries to play it off as a Major Injury Underreaction, but his stuttering gives him away.
  • One-Wheeled Wonder: In his usual appearance, where he balances his rectangular body atop a single comically tiny wheel.
  • O.O.C. Is Serious Business: Mettaton during your last fight against him. He starts as his usual self shamelessly proclaiming himself the brightest star of underground and soon-to-be of the surface. As the battle drags on he'll start to lose his composure and outright call the player out for their "weakness". Also in the ending where he rules the Underground, he becomes somber and saddened over Alphys' disappearance and wishes he had a chance to treat her better.
  • Opportunistic Bastard: When Alphys asks him to play the heel against the human, he plays along so he can derail the plan later. In the ending where he becomes ruler, he starts by unironically thanking you for your "hard work" (i.e. killing Toriel and Undyne), as this paved the way for him to seize power.
  • Peek-a-Bangs: Mettaton EX has his right eye covered with hair, which Dummied Out sprites reveal is because the right part of his face is unfinished. Mettaton NEO, keeping with the subtle theme of left eyes being shown in serious situations, has obscured his right eye.
  • Percent Damage Attack: The penalty laser he uses during his quiz halves your HP and as a result cannot actually kill you. If you do hit 1 HP, he'll just skip right to the end of the quiz.
  • The Perfectionist: An unusual Sanguine example. He pushes everyone who works for him to attain his high standards, and refuses to accept anything he doesn't deem to be as good as 'how they do it on the Surface'.
  • Pet the Dog: He really cares about his cousin, Napstablook and his old friend Shyren, enough to go into showbiz with both of them in the Pacifist ending. If you spare him but kill Undyne and Toriel, he becomes king and has a statue built in Alphys' honor, admitting that he was cruel to her.
  • Pinocchio Syndrome: Hinted. He is so fond of humans he founded a fan club celebrating them, and the body he asks Alphys to build for him is the most humanoid thing you see underground, being basically a metal pretty boy. It even has its own visible SOUL.
  • Plot-Irrelevant Villain: Mainly from a meta perspective. In the Pacifist run he's the odd one out of the main characters; while the other major bosses are meant to present serious questions about the player's morality, with Mettaton what you see is what you get — a silly, if deeply layered, drama queen who works more as an extension of Alphys's character for the plot. Averted, however, in the Genocide run; see Threshold Guardian below for why.
  • Point of No Return: Downplayed for the Genocide route. Once you fight him in his NEO form, you're either locked into the route (if you do kill all the enemies), or abandoned it completely (if you don't). However, up until you meet the Fallen Child, you can quit and reset the game at any time with no consequences. Which makes sense, since Sans is trying to ensure that you do.
  • Pointy-Haired Boss:
    • In addition to his celebrity life, he's also the owner/boss of the MTT Resort located between Hotland and The Core. And he is terrible at managing the place. Even disregarding Burgerpants' complaints about him, he has put many bad ideas into use, including: Adding a statue of himself to the fountain that shoots a stream of water onto the lobby floor, not providing room keys for the hotel rooms so patrons have to pay full price just to get back inside, hiring a janitor that constantly drips slime from his chin (resulting in him continually cleaning up the same spot), and the resort's restaurant making patrons have to reserve not just their meal time in advance, but also all their food, tables, tableware, water, etc.
      Burgerpants: ...And every time we try to change something for the better, he vetoes it and says "that's not how they do it on the surface." Oh! Right! Humans are always eating hamburgers made of sequins and glue.
    • Mettaton is terrible at ruling the Underground in his version of the neutral ending, completely neglecting the economy and the educational system as well as no longer even trying to reach the surface.
  • Pre-Final Boss: He's the last boss you face before Asgore on the Neutral route and Sans on No Mercy, albeit the latter isn't much of a "fight".
  • Red Oni, Blue Oni: If you get the Mystery Key, you can discover he used to be the Red to Napstablook's Blue.
  • The Rock Star: While he's primarily an actor in his various shows first and foremost, Mettaton has the personality of one: being loud, arrogant, and flamboyant while also showing that he's capable of singing. Then his EX form shows he has the look of a rock star as well, of the David Bowie variety.
  • Shadow Archetype: As the Evil Counterpart section above explains, Mettaton represents what Papyrus would be if he became a serious threat similar to Flowey and Mad Dummy before him, if his quest for glory implied betraying the people who love him and if his narcissism overshadowed his qualities.
  • Shameless Self-Promoter: The reviews in MTT Resort are clearly biased in Mettaton’s favor. Parodied in that these reviews are written by Mettaton himself.
  • Shaped Like Itself: The game occasionally gives scent-based information in the status window, such as saying that Papyrus "Smells like bones." All the game can muster for Mettaton is "Smells like Mettaton."
  • Shipper on Deck: Near the end of the Pacifist run, he says that Alphys and Undyne should just kiss each other already. Undyne is insulted, but Alphys thinks this is a good idea.
    "Oh my god! Will you two just smooch already!? The audience is dying for some romantic action!"
  • Shock and Awe: Mettaton zaps you with electricity if you get a question on his quiz wrong. Mettaton EX's heart shoots lighting when it attacks directly.
  • Sissy Villain: Even as a box-on-wheels, he's very flamboyant, calls the protagonist things like "sweetheart", and shows that he has no problem crossdressing for a role if the musical scene is any indication. His EX form is also an even more flamboyant rock star akin to Michael Jackson or David Bowie, and once the player gets into his old house, they find the whole place covered in pink. The typical "Sissy Villain/Manly Hero" dynamic, however, is absent, since the protagonist is a small child of Ambiguous Gender.
  • Sitting Sexy on a Piano: Visited Undyne's house only to sit on the piano and eat grapes.
  • So Proud of You: If you defeat him on the Pacifist route, he seems to be feeling this towards the child, saying that they've more than proven themselves to be strong enough to defeat Asgore and protect humanity. He has absolutely no malice or hard feelings about his defeat when he says this.
  • Sophisticated as Hell: He's usually well- (if super-dramatically-)spoken. He also has a scene in which he puts on a dress and sings you a soft little song under a shower of rose petals that includes the lyrics "It'll suck, and then you'll die a lot", and reacts to the player typing "Toby" in part of his final boss battle with "What the hell is that?"
  • Spanner in the Works: Mettaton was going to go along with playing the bad guy so that Alphys could save you and be the hero. Once you are too close to Asgore, however, he drops the charade, tells you what Alphys did, and plans to reap your soul.
  • Start of Darkness: Mettaton was once a shy ghost who had dreams of becoming a big star, but promised his cousin Napstablook that he would never leave them. After meeting Alphys, who eventually built him a robotic vessel to inhabit, he decided to go back on his word and left the snail farm to become famous using his new body. It only got worse from there as the more popular Mettaton got, the more rude and narcissistic he became, culminating in him trying to murder Frisk and take their soul in order to become famous on the surface. He gets better in the Golden Ending, fortunately, as he reconciles with Napstablook and Alphys.
  • Stone Wall: In his normal form, Mettaton is practically indestructible, but his attacks (except his zaps) aren't very powerful. His EX form, on the other hand, has much more balanced stats (at least since the 1.001 update).
  • Suddenly Voiced: Lets out an "Ohhhh yesssssss!!" when you flip the switch that triggers his EX form.
  • Tactical Suicide Boss: In his EX form, Mettaton has a weak point in the shape of a heart not unlike a human SOUL... which he'll reveal in order to make puns and attack with it, allowing your yellow SOUL to shoot it. Note that this doesn't actually kill him (that can only be done by physically attacking); its only purpose is to knock off his limbs and lower his desired ratings count.
  • There Was a Door: How he makes his entrance at Alphys' lab, with unexpected grandeur. Checking the hole he made in the wall reveals the space inside it is actually quite small, implying he was camping out inside Alphys' wall the entire time she was talking to you beforehand.
  • Threshold Guardian: Mettaton is an unusual variant of this trope, as you fight him very late in the game, but he isn't a threshold guardian to a heroic adventure — he's a threshold guardian to the No Mercy run (just short of an outright Reset). If the player is having second thoughts about killing everyone in the game, Mettaton's NEO form is the player's last chance to back out without doing the aforementioned Resetnote  — if the player fails to kills enough Hotland encounter monsters (around 40) before fighting him, Mettaton decides you're not irredeemable and sets you on Neutral instead.
  • Tin-Can Robot: His typical appearance. Becomes a Ridiculously Human Robot when he transforms into Mettaton EX.
  • Tranquil Fury: As the player knocks his limbs off during his final boss fight, his usual cheery, lively playing-to-the-crowd manner steels over and his attacks get more aggressive and direct to the point that in the time it takes to fully meet his SPARE requirement, you can have him wordlessly, motionlessly spamming lightning at you with a fixed, clearly effortful smirk.
  • Trap Master: Far more than Papyrus and his puzzles. However, Alphys is able to disable most of them. Of course, it's all part of her little show, and none of the traps put you in any real danger until he decides to stop playing along.
  • Troll: Has his moments of this. Especially when you learn he isn't an AI. His question about who Alphys has a crush on and "Would you smooch a ghost?" are notable examples, as is his Early-Bird Cameo as the control panel in the randomly generated puzzle in Snowdin; it wasn't a malfunction, he was screwing with Papyrus for reasons only he probably knows.
  • The Usurper: In the Neutral Ending where he becomes ruler, Sans states he "just kind of... took over?". By contrast, the other characters who become ruler in the Neutral endings either inherit legitimately (Toriel, Undyne) or are elected by popular support (Papyrus, Annoying Dog, Alphys).
  • Unexpected Shmup Level: Or rather, Unexpected Shmup Boss. The yellow SOUL feature you get from Alphys gets used more extensively in the fight against Mettaton EX, where you have to shoot his bombs, legs, and soul to fight back — the only time in the game where you have any sort of direct offensive capability on the bullet board.
  • Unrobotic Reveal: If you find the door that the Mystery Key opens, it's revealed that he's actually Napstablook's cousin, given a physical form by Alphys so he could make it big in show business.
  • Vocal Dissonance: After becoming Mettaton EX, he speaks in a deep voice that doesn't quite match his flamboyant looks. Aside from that, he also keeps the same Voice Grunting. This trope is then subverted by his higher-pitched voice when he says "yeah" if he is hit.
    "Ohhh yess!"
  • Voice Grunting: Stereotypical robot beeping.
  • Viewers Are Geniuses: In-Universe: Considering Mettaton's infamous train question...
  • Walking Spoiler: When the player first meets him, he is a stereotypical (if snarky and affable) killer robot hellbent on their destruction. Truth is, it was all an act to make Alphys look better. He is actually a ghost inhabiting a machine that wants to take your soul and become a star on the surface. By extension, his EX form also leads to this.
  • We Can Rebuild Him: Alphys claims as much after his boss fight, whether he was destroyed or not. It's supposed to be implied that, due to actually being a ghost inhabiting a robot, killing Mettaton EX means he's gone for good (to the point where it can be a deciding factor in Alphys' implied fate) — at least if, like the Mad Dummy on the No Mercy route, he's grown sufficiently attached to his body.
  • Weird Trade Union: He apparently abides by one, since he provides the Human with a genuine "union-mandated" break during battle as Mettaton EX.
  • Well-Intentioned Extremist: The real reason he wants to kill the player is to deny Asgore their SOUL, preventing the war between monsters and humans from resuming. Using the SOUL to pass the barrier and to make it big in the human world is just a bonus.
  • Wholesome Crossdresser: He wears a blue ballgown for the musical, and his EX form wears high-heels, and is, of course, dressed head-to-toe in pink. If you backtrack and talk to a lion-like monster after the musical bit, the lion comments that Mettaton looked really cool in his dress, and it "sort of makes [him] feel like [he] could wear one, too!" Awwwww. In the True Pacifist epilogue, if you talk to the lion again, you find out he decided to go for it — and, in fact, Mettaton gave him the very same dress he wore!
  • World of Snark: His TV shows seem to be this, if what the Human Child goes through is any indication.
  • Worthy Opponent: He frequently comments on how brilliant Dr. Alphys is whenever she helps you defeat him. Subverted, as they're not really enemies. In fact, they're close enough friends for Mettaton to agree to play an evil killer robot so she could be the hero.
  • Zero-Effort Boss: Justified: Mettaton NEO is the most standout example on the Genocide Run. Not only does he go down in one hit, he never attacks. That's because he's not there to FIGHT you, but to STALL you to buy the evacuation more time. It's even in his battle stance.