You're gonna have to try a little harder than THAT!
~ Undyne the Undying on Love Part 1

Undyne is a major protagonist and an ally of Frisk who first appeared in Season 1's Finale, Continue. Undyne was the heroine of the Underground, but when Asriel and Chara shattered the Barrier, Undyne became a police officer instead.

Undyne is voiced by Adox0graphist, who also voices Asriel.


Undyne is a female humanoid fish monster who has blue scales with yellow teeth, a black eye patch that covers her left eye, and a long red ponytail that reaches her back. On both sides of her head are blue and red fins. Her right eye a black pupil and a yellow sclera. In Love Part 1, her eye patch was gone and she now has an eye with a grey pupil and a yellow sclera.

In her Undying form, her pupils become yellow, her sclera turned black, she has no eye patch (which revealed an empty socket), and a red ponytail. Also, she wears dark grey armor, boots with pointy shoes, and white gloves.


Undyne has a very heroic and optimistic personality. She also cares for others and does what she believes is best for them. This is shown as she likes to cook food so she could try and convince Papyrus to do other hobbies in the game.

She is also honorable, so she always wants battles to be fair, as seen in the game where she provides Frisk a spear to block her attacks. This event didn't happen with Bete though, which could mean she wants Betty to be dead as soon as possible, showing that anyone she sees as an irredeemable enemy does not deserve honor or mercy. This doesn't detract her from her heroism, however, as she is always willing to help however she could.

She cares a lot for Alphys, as she ran to the Nullifier Room in order to rescue her. Alphys told her that anime is actually human history, she then says that human history is cool, and mentions that humans were able to hold swords 10x their size.


  • Spears: Undyne's main weapons are spears that she can summon from nothing. She can also increase or decrease their size as shown in Do or Die. She can also use yellow spears that can also switch directions at will. Some spears can also rise from the ground. Also, the bigger her spears are, the stronger they are.
  • Determination: If Undyne's HP is 0, she holds onto her Determination to fight, or if the situation is really bad, she reforms into Undyne the Undying.
  • Determination Manipulation: Undyne is able to manipulate her own determination.

  • Superhuman Strength: Undyne has incredible strength as she's known to knock anyone dead.
  • Superhuman Speed: Her speed is unmatched, as she can fight with lightning fast reflexes and agility.
  • Spear of Justice: It's a Determination special attack that can be used in the Undying form. Undyne's Determination spear is a powerful weapon, extremely overwhelming and destructive. This special attack was only used in the Love Part 1 episode, where it blew up Bete Noire.
  • Regeneration: After monsters gained physical matter over time after being around humans and eating their food; because of this, Undyne would be able to contain determination without melting as she fought Bete, Thanks to this and her determination, Undyne is able to regenerate her injuries/damages sustained in battle.
  • Hypersonic: Using Love, Undyne can move at speeds to where you think she was teleporting but she was just running, presumably as a deception tactic.

Official Comics

Timeline 1 Comic [1]



Undyne appears at the beginning of the animation, where Papyrus was waking up Sans. Here, she was shown to be talking to Gaster.

Later, when the barrier was broken, Undyne was seen watching the HATE Bubble break and was also seen with Toriel, Papyrus, Sans, Frisk, Alphys, and Asgore at The Surface.

My Sunshine

...I'm proud of Undyne for becoming a police officer.
~ Frisk talking about Undyne
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Undyne in her Police Officer outfit.

Undyne managed to make a cameo at the beginning of My Sunshine. She appears when Frisk mentions that she became a police officer.

Later, Undyne and Alphys were seen watching the reunion on TV.

Do or Die

Undyne plays a much larger role in this episode than the other two episodes. She first appeared at the police station, where Asgore and Papyrus were held behind bars. Mrs.Grey soon asks Undyne to open the cells for both of the monsters. Undyne refused at first, not knowing that she was the leader of the Anti-Monsters Department (or AMD). Jessica then shows her ID card to Undyne. Undyne then opens the door for Jessica, who speaks with Asgore before she is taken to Papyrus to apologize for playing a part in Sans's death.

A little bit later in the episode, Undyne arrives at Gaster's Lab, with Papyrus, Jessica, and Asgore. Gaster soon tells Undyne to help fight against the Bete's pink blobs to protect other humans from being killed by them.

Near the end of the episode, Undyne is seen at Gaster's lab, waiting for Alphys to arrive, only to find an injured Gaster, with Jessica helping him. Jessica tells her that Alphys set up a trap to kill that "thing". In a fit of worry, she quickly ran fast as she could to the CORE Expansion Nullifier Room. Sadly, when she arrived, Bete tricked her into killing her love interest, Alphys. She is then attacked by her, who manipulated the spear she just threw to (unintentionally) kill Alphys. Her HP decreases to zero, but with her Determination, she reforms herself as Undyne the Undying to fight Betty once more.

Love Part 1

(Betty: Ha! You think your spears are stronger?) Undyne: (grins) I don't think so. I know so.
~ Undyne to Betty
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Undyne getting ready to fight Bete Noire.

Undyne was seen fighting Bete, in her Undying form. She has a better chance of beating her than the others, due to her having DETERMINATION. Bete scorns her and the strength of her spears, but Undyne is unfazed.

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As soon as they start fighting, Bete is quickly overwhelmed by Undyne's immense strength, confused at her being alive, and having Determination even though she claims that Monsters can't have Determination. Eventually, Bete began to lose her temper and activated Rhabdophobia right before Undyne launched an enormous volley of spears. She used Rhabdophobia to take control over the volley, but Undyne is unfazed, saying she can have them and proceeds to summon thousands more. Bete's stolen spears are shredded in the storm of Undyne's spears.


Undyne charging her "special attack", The Spear of Justice.

Kumu, again tried to protect Bete, to no avail, and Undyne soon summoned her Spear of Justice. She didn't hesitate to throw it, which created an enormous crater in the middle of the forest. Bete clearly didn't survive the blow and her body was slumped on the ground, causing her body to slowly dissolve.

Kumu tried to wake her up, and desperately ate the entire HATE Vial to revive her. Undyne launches another normal spear, in hopes of finishing the job, the smoke soon dissipated. Luckily for Bete, she was back to normal, except that her hair was completely pink, and her scleras are black, and that HATE had taken full control of her. Bete attacked once again with her ability to teleport, slightly surprising Undyne. But she refused to stop fighting and knocked her away, but she quickly recovered from the attack. She attacks once more with her scythe, but Undyne was able to dodge it. On the second swing, she is slashed diagonally across her chest and summoned her spear to finish Undyne. But Undyne knocked her back and Undyne heals her wound. Bete steps forward, and the black in her eyes begins to spread across her face, then quickly recedes, along with the pink in her hair. She falls to her knees, coughing up HATE.

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Undyne turning back to normal after Bete Noire escapes from their battle.

Undyne attacks once again, but Kumu pulled her out of the way. Bete stated that she doesn't know what's happening to her, and the two retreat. Undyne reverted to her normal form and began to cry due to the grief of losing Alphys. Her eye-patch disappeared revealing a silver eye and a scar on her left eye.

Being greeted by Papyrus upon her arrival, Undyne returned home. He then took her to bed.

Love Part 2

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Undyne sleeping at the beginning of Love Part 2.

During the nighttime, Undyne is seen laying down asleep in her bed when the episode began. Later, while she was laying down, Gaster decided to ask her about her battle with Bete. She explained that everything was going smoothly but, before pulling off the finishing blow, Bete absorbed a strange liquid. Upon Gaster's realization that Jessica had lied to everyone about giving her the HATE vial, Gaster lashed out at her and she partially lost her Integrity. She was then told to stay with Undyne.

My Promise

How am I supposed to live with this guilt? I just want to tell her I'm sorry.
~ Undyne being consumed with guilt

Undyne with Jessica Grey.

Undyne is first seen with Jessica Grey. Undyne then tells Jessica that they shouldn't feel bad and that she doesn't blame them for what happened. Jessica says that it's not only that that is bothering them, it's that everything that she has done in her life are mistakes, and that other people are the ones suffering because of her actions instead of herself. She brings up that she harmed her daughter, Sans, Dr. Gaster, and Alphys. Undyne tightened their grip on their blanket and said that Alphys' death wasn't because of Jessica leaving Alphys. Jessica then insists that it's her fault because she had let go of the black substance and let Betty get to it, and because of that, Alphys got killed.

Then, Undyne admitted that it wasn't Betty who killed Alphys and that she was the one who killed Alphys, Jessica couldn't believe that Undyne killed Alphys and it was just a mistake, Undyne then says that it was a mistake. She acted before thinking, and because of that, her attack killed Alphys instead. Undyne then says that the guilt of her killing Alphys is torturing her, and questions how she can live with that guilt. Jessica stated that she understands what Undyne is feeling, to have an unbearable guilt in her heart and that nobody deserves to feel that way, certainly not Undyne. Undyne uttered that it hurts her whenever she thinks about what she did, she wants to forget what happened, but she doesn't want to forget Alphys. Jessica expressed that it isn't about forgetting about what she did, it's about accepting how bad it feels in order to move on. Suddenly, Jessica hears someone knocking, she assumes that it's the others and leaves the room in order to let them in.


Jessica realized that it wasn't the others, it was pink blobs trying to break into the house. Undyne then helps Jessica with the pink blobs; killing one of them in the process. Undyne then starts killing the pink blobs one by one. Jessica tries to kill off one of the blobs using the AMR, but her soul suddenly cracks, leaving her to be vulnerable.


Undyne frozen in fear.

Undyne then tries to help Jessica by throwing a spear at the blob. However, this caused Undyne to remember her killing Alphys that causes her to stand still due to trauma. The pink blob ends up attacking Jessica in the chest, Asgore then throws his trident at it in order to kill it.

After that, Undyne is seen again with Asgore, Toriel, and Frisk. Asgore suggested that Undyne and Gaster should take care of the school just in case Bete or the pink blobs are going to attack the school again. Asgore then says that Undyne can do something for Alphys, and help Alphys break free from Betty's control, not knowing Alphys is dead. This causes Undyne to remember again what had happened, she was about to say that she doesn't think she will be able to do protect the school, but she is interrupted with an explosion in the city. After this, Undyne was never seen again in the episode.

Game Over


Ronan introducing himself to Undyne.

Undyne is first seen evacuating the civilians. Ronan mistakes her for a normal civilian until she mentions that she is a member of the police. Ronan is surprised since he mentions that he has rarely seen monsters in the city he works in and much less serving as a police officer, this likely hints at the other two continent's issues. They both introduce each other, as well while shaking hands. Ronan suddenly gets a call from an anonymous person. Undyne watches Ronan and after the call, she asks him if everything's okay, Ronan replies that he isn't sure and offers Undyne to come along with him to the Safe Perimeter #1, and she agrees.


Undyne with Ronan.

After going to the Safe Perimeter #1, Undyne meets Rave. She doesn't have any dialogue throughout Ronan's conversation with Rave and after this, she was never seen again in the episode.

In Part 2 of Game Over, we first see her with Ronan when she's asking him about the deal with Rave. Ronan then gives her a backstory on why Rave is so mad at Jessica.
Undyne remembers

Undyne hesitating to throw her spear due to how Alphys had died.

Later, in the city she's seen with Ronan. Ronan encourages her to fight on and motivates her with saying that what happened to Alphys should make her want to ensure that no one ever has to deal with that pain. She then sees Hugo with Zachary and his mother. She first yells and questions why they are there, to where Hugo says Zachary had something important to tell. She doesn't believe them at first but then Zachary's mother tells her that it is important and that Zachary can sense magical energy. Zachary then says he feels something under the ground, something big in huge, referencing the giant Kumuzilla.Ronan then notices it moving to the area Gaster and Jessica are in. Undyne then hurries with Ronan.

She, with Ronan witnesses as the giant Kumuzilla heads for the school. After Ronan fires his Justice beams at the smaller Pink Creatures, Undyne notices another Pink Creature sneaking up on him, she prepares to throw a spear but gets hit with the memory of what happened to Alphys when she threw a spear again. Ronan is saved by Hugo, however, Hugo almost gets hit by the giant Pink Creature but then Ronan takes the hit for him after Ronan gets hit by the Pink Creature to the point his whole face is bleeding, Undyne is seen looking in shock.

At the final scene, she is seen preparing to fight against the Kumuzilla and protecting Hugo with an unconscious Ronan.


  • At the end of Do or Die there is a hidden text by Bete Noire that says "You think your spears are stronger?" This text obviously refers to Undyne's spears.
  • Despite the fact that no one knows Undyne's Undying form, Gaster knows the Undying form.[2]
    • Since Frisk has attempted to do the Genocide Route on Megalomaniac, Frisk knows the Undying form aswell but that doesn’t matter as Frisk is entirely erased from the timeline.
  • Bete's power is not strong enough to kill Undyne.[3]
  • Bete made Undyne kill Alphys because absorbing her soul would've given her little to no magic to feed off of. This could mean Alphys has no magic at all.[4]
  • When Undyne said in Love Part 1 that she was greatly hurt, she obviously meant that she was emotionally scarred because of accidentally killing Alphys.
  • In Undyne's battle with Betty, Akumu shielded Betty from Undyne. Before the episode came out, Akumu as a shield was seen as impenetrable, however she easily cut through Akumu with her spear; proving her great strength.
  • Undyne can create her own Determination. 


  2. Despite the fact that no one's knows Undyne's Undying form (except Frisk), Gaster knows the Undying form. (Link)
  3. Bete's power is not strong enough to kill Undyne. (Link)
  4. Bete made Undyne kill Alphys because absorbing her soul would've gave her little to no magic to feeding off on. (Link)


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