Guess you don't want to join my fan club...
~ Mettaton NEO's last words.


~ Mettaton

Mettaton is the tertiary antagonist in the 2015 indie game Undertale. He is a ghost possesing a robot body created by Alphys, built to be a TV entertainer. Alphys later added human combat features, but supposedly tried to remove them. When Frisk arrived, Alphys came up with a plan to make herself lookgood to Frisk, activating puzzles and traps and getting Mettaton to antagonize Frisk so Alphys can “rescue” them from him.

Neutral Route

During the Neutral run of the game, the scientist Alphys will tell Frisk that she has created a robot known as Mettaton with anti-human killing functions, but wanted to remove them when she saw Frisk coming by camera. Unfortunately, when she tried to remove them, she made a mistake and Mettaton is now a bloodthirsty killng machine. Right after, Mettaton will break through a wall and start hosting his "game show," complete with confetti and flashing lights. In this game show, Frisk must answer a series of questions correctly. If they answer a question wrong, Mettaton will electrocute them. On one of the questions, Alphys burst in and yells out the answer out of excitement. As a punishment for yelling out the answer, Mettaton's next question for Frisk is, "Who does Dr. Alphys have a crush on?" If Frisk answers "Undyne" then Alphys will start to blush and Mettaton will begin to tell Alphys that guessing her crush was simple. Once Frisk answers all the questions he has, Mettaton will blast off.

Some time later, Frisk will enter a kitchen set where Mettaton will is, and he orders Frisk to get ingredients for his show "Cooking With a Killer Robot." Once Frisk has all the ingredients, Mettaton will remember that there's one last ingredient for the cake he's making—a human soul. He then gets out a chainsaw and slowly closes in on Frisk. Alphys suddenly interrupts by calling Mettaton and asking if he could possibly use a substitute. Mettaton exclaims that that's a great idea and motions over to a can of MTT Brand Always-Convenient Human Soul Flavor Substitute sitting on a counter several feet away and orders Frisk to get the object. Before they can, the counter shudders and expands, raising the can high into the air. Mettaton tells Frisk that if they do not get the can in under one minute, they will go back to the original plan of using Frisk's own soul. Frisk is given a jetpack by Alphys via cell phone button and must get the can within one minute. As Frisk flies through the air, Mettaton throws ingredients such as eggs and flour at them to slow them down. Once Frisk gets it, Mettaton leaves, defeated.

Later, while Frisk is walking around in Hotland, they wander into a room in which Mettaton is reporting the news, and the robot asks them to find something newsworthy to report. No matter what Frisk chooses, the item will turn out to be a bomb, and Mettaton then reveals that every single object was actually a bomb. This time, Frisk must deactivate the bombs using a defuser (also installed on their phone by Alphys) or else a giant bomb will explode in 2 minutes, according to Mettaton. Once Frisk deactivates all the bombs, Mettaton tells them that the bomb will not explode in 2 minutes, but instead in 2 seconds. Fortunately for Frisk, the bomb is apparently faulty since it fails to explode and once again, Mettaton leaves.

Frisk encounters Mettaton yet again, but this time, Mettaton is wearing a blue dress. Mettaton starts calling Frisk his "one true love" and starts serenading Frisk as pink petals fall in the air, saying that they should run away before they die many times in the dungeon. Mettaton then opens a trap door beneath Frisk, making them fall into a room where he brings up a tile puzzle Frisk must complete. They are challenged to do so under 1 minute, or else they will be burned by walls of flames. When one minute passes, the flames start to slowly reach Frisk until it stops due to Alphys hacking into the firewall and turning it off. Mettaton recalls that the green tile means that Frisk must fight a monster, and states that the monster is none other than himself. He begins to fight Frisk, and Alphys immediately calls and tells Frisk a way to fight back against Mettaton. Frisk pushes a yellow button on the phone and Frisk's soul turns upside down, becoming yellow. Frisk is then able to fight back against Mettaton using a bullet-shooting power. Mettaton flees in defeat once more, but not before showing that he seems to have lost interest.

Frisk meets up with Mettaton one more time at the end of the Core, but this time he prevents Alphys from interrupting by locking the door so Alphys can't enter, and then exposes the fact that everything he had done up until now was all an act to make Alphys look good in Frisk's eyes, as well as the fact that he has no desire to harm humans, only wanting to entertain. Red lights around the pair will turn on and the platform they're on shoots upward, with Mettaton announcing his new show "Attack of the Killer Robot." Frisk attempts to use the yellow soul power to defend themself, but Mettaton, unaffected, tells them that it won't work on him. Alphys then calls Frisk and tells them to turn Mettaton around so that they can flip the switch on his back. Frisk tricks Mettaton by telling him that there's a mirror behind him and once Mettaton turns around, Frisk flips his switch. After the robot shakes violently and his screen flashes rapidly, the whole room flashes with white light and Mettaton says his trademark "OHHHHHH YESSS" in a deep voice.

As spotlights switch on and fog starts clearing, Frisk can see a humanoid silhouette emerging where the rectangle once stood. Mettaton EX then reveals his new form, promising to make Frisk's last moments absolutely beautiful. Mettaton EX and Frisk battle on live TV until Frisk either kills Mettaton, or raises the ratings for Mettaton's show high enough to have him stop the battle to have a viewer call-in session. If the ratings go high enough and Mettaton survives, Napstablook as well as some of Mettaton's other fans tell him how much they loved his show and express their remorse about him leaving, convincing him to stay in the underground. Finally, Mettaton informs Frisk that the battery consumption of his new form is inefficient and that he will shut down soon. Right before he shuts down, he cheers Frisk on and thanks his audience. Once Mettaton's control over the door has been stopped, Alphys comes in, concerned. If Frisk killed Mettaton, his rectangular body will be lying on the floor, broken, and Alphys is deeply saddened, saying that she can always build another robot (though that is a lie). If Mettaton simply ran out of battery, she sighs in relief. Whichever action Frisk chooses, once Mettaton is dealt with, they can progress out of the Core into New Home.

An ending can occur if Frisk kills Toriel and Undyne but spares Mettaton, where Mettaton becomes the ruler of the Underground and brainwashes every citizen with his television show. Any more humans who fall into the Underground can join his fan club for free. Mettaton also builds a statue to Alphys in apology, as he was not the greatest to her, but was never able to find her. Sans and Papyrus (if he is still alive) become Mettaton's agents and enjoy their new lives (despite everything being off like it was before).

True Pacifist Route

If the requirements have been met for the route, Mettaton will appear for a brief time when Frisk's friends have assembled in Asgore's throne room, sticking his leg on screen and telling Undyne and Alphys to kiss, as the audience has apparently been dying for some romantic action. In the segment where Frisk can take a walk through the underground and talk to all of its residents, Mettaton can be found with Napstablook next to the two oblong pastel-colored houses in Waterfall. He thanks Frisk for opening the barrier and informs them of his plans to finally perform with Napstablook and Shyren before asking them what kind of merchandise of him humans would like. In the end credits, Mettaton can be seen as a successful star, performing onstage with Napstablook, Shyren, and even Burgerpants.

Genocide Route

During the Genocide Route, when Frisk first encounters Mettaton in Alphys' lab, Mettaton simply threatens them and runs away. Mettaton is not seen at all in the Genocide route until Frisk makes it to the end of the Core. At the end, Mettaton will confront Frisk and threaten to show them his form. Once Frisk steps forward, Mettaton transforms into Mettaton NEO, sporting winglike lights and an arm cannon. However, in his new form, he never attacks, and doesn't do anything at all until Frisk hits him once, causing him to explode. Notably, unlike in his Neutral and True Pacifist incarnations, Mettaton doesn't leave any semblance of his body behind after being dealt with. Furthermore, if the player has not fulfilled the requirements of killing everyone in Hotland/the Core, Mettaton acts as the the last way to go back on a Neutral path. Even though he is killed in one hit again, he remarks that Frisk was holding back and that they are not truly evil, so he can rest easy knowing Alphys as well as the humans above ground will live.


Sorry, Blooky. My dreams can't wait for anyone
~ Mettaton's final journal entry, before gaining a body.

Down the alley on the right of MTT Resort, the shopkeepers Bratty and Catty sell a "Mystery Key" for 600 gold. This key unlocks the pink house next to the blue one belonging to the ghost Napstablook. Inside are several of Mettaton's journals, in which his backstory is revealed. He was originally a ghost, and is Napstablook's cousin. Eventually, he met Alphys, who made the the robot body for him as a way to get him the stardom he always dreamed of. Mettaton eventually left to become a celebrity, essentially abandoning his cousin.