Undertale Wiki

We've Moved! Just as Gamepedia has joined forces with Fandom, this wiki had joined forces with our Fandom equivalent. The wiki has been archived and we ask that readers and editors move to the now combined wiki on Fandom. Click to go to the new wiki.


Undertale Wiki
For the track named after this character, see Undyne (Soundtrack).
Character Information
Also known as
Undyne the Undying*
First Appearance
Alphys (love interest)
Asgore (friend/mentor)
Papyrus (trainee)
Spear of Justice
Battle Against a True Hero
But the Earth Refused to Die
Battle Information
1500 (Normal & Faux)
23000 (Undying)
50 [7] (Normal)
41 [10] (Faux)
99 [12] (Undying)
20 [0] (Normal)
21 [10] (Faux)
99 [5] (Undying)
EXP On Kill
500 (Normal)
1500 (Undying)
Gold On Win
Plead, Challenge (Normal)

— Undyne before her battle

Undyne (/ˈʌnˌdaɪn/ UN-dyne[1]), known as StrongFish91 on the UnderNet, is a fish-like monster that leads the Royal Guard. Clad in her full suit of armor, she pursues the protagonist through the entirety of Waterfall and is frequently evaded or inadvertently thwarted by the Monster Kid.





Undyne prepares to throw her spear at the protagonist.

Undyne debuts in armor varying in light and dark shades of gray, but without armor, is a piscine, anthropomorphic monster. She has blue scales and a long red ponytail. She has red and blue fins on the sides of her head, and a pair of sharp, yellow, protruding teeth. She wears red eye shadow and has an eyepatch on her left eye. She also wears a black tanktop and jeans. Her eyes have black vertical pupils and a yellow sclera. Undyne has no nose. She is 6'11.

Alphys Date

During the date with Alphys, Undyne wears a white turtleneck under a black leather jacket, pants, a light-colored eyepatch, and lets some of her hair down.


Whenever she persists through Determination after her HP reduces to zero, her pupils turn white, and her sclera turns black. She no longer has an eyepatch, and her newly revealed empty eye socket emits a flashing light. Her hair spikes at the ends and her fins become more rigid and pointy. She also appears to have donned a new set of darker colored armour with souls/hearts on her chestplate and on her new white gloves, accompanied by boots with pointed toes.


Undyne is passionate about everything that she does. She acts quickly on her ideas and is steadfast in her beliefs.[2] Though she wants to defeat the protagonist, she also tries to be fair and offers an explanation of how Green Mode works. Asgore taught her the value of pacifism,[3] which is why Undyne sees the protagonist as "a wimpy loser with a big heart." When the protagonist first encounters her, she fights to further Asgore's plan of collecting seven human SOULs but, if the protagonist shows mercy, Undyne just as quickly defends them from Asgore.

She loves to help others and mentors Shyren and Papyrus in various skills. Undyne dislikes puzzles, loves japes,[4] and enjoys anime, an affinity she shares with her romantic interest, Alphys. Since Alphys told Undyne that anime is actually human history, Undyne regards human history as exciting and cool.[5]

Out of all encountered monsters, Undyne possesses the most Determination. She melts before her death, implying that her body cannot handle the amount of Determination she has.

Main Story

Neutral Route



The protagonist initially encounters Undyne after entering Waterfall, where Undyne stands on top of a ledge. If alive, Papyrus approaches her and attempts to convince her not to harm the human. As the protagonist continues, the grass rustling alerts Undyne to their presence, and she scopes out the grass for a moment before retreating.

Undyne follows the protagonist throughout Waterfall and repeatedly attacks them, but the protagonist always evades capture by either dodging her attacks or due to Monster Kid's interference. Later on, Undyne approaches the protagonist as Monster Kid hangs on to the side of a bridge. If the protagonist saves the Monster Kid, they will protect the protagonist from Undyne. If the protagonist does not help the Monster Kid, Undyne will save them instead.


— Undyne when enraged

After this, Undyne confronts the protagonist and stands atop a crag while giving a monologue that she has practiced many times before.[6] However, she cuts the monologue short because she forgot the rest of it[7] and launches head-on into battle.

After Undyne chases the protagonist into Hotland, she collapses because her armor heats up. The protagonist can offer Undyne a glass of water, spill all the water in front of her, or continue into Hotland. If she receives water, Undyne stands up, looks around, and slowly returns to Waterfall.

True Pacifist Route

I'll make you like me so much... Your WHOLE LIFE will revolve around me!! FUHUHUHUHU!!!

— Undyne on her date with the protagonist.

If the protagonist befriended Papyrus, he calls them during Undyne's chase and suggests that they and Undyne should hang out at her house. If the protagonist gives Undyne water, Undyne will befriend the protagonist if they have no EXP. After Undyne's battle, the protagonist can backtrack to her house and begin their hangout with her.

Undyne is initially hostile to the protagonist[8] but changes her attitude when Papyrus presents befriending the human as a challenge. She realizes that becoming "besties" with the protagonist would be "the perfect revenge," and says that the protagonist will feel "enamored" with Undyne by the end of their date. Undyne discusses her training with Asgore over tea and suddenly realizes that Papyrus's cooking lesson usually occurs at this time. She insists that her and the protagonist bond over cooking, which ends in Undyne's house catching on fire. Humiliated and feeling that she failed at befriending the protagonist, Undyne battles the protagonist and offers them the first hit. After the protagonist deals only one damage, Undyne realizes neither of them wants to harm one another.

Because her house is engulfed in flames, Undyne moves into Papyrus and Sans's House.

After the protagonist completes a Neutral Route, they can backtrack from the CORE into MTT Resort, and Undyne will call them to ask for a favor. In Snowdin Town, Undyne gives them a letter that she asks them to take to Alphys in Hotland. The protagonist gives Alphys the letter, but she mistakes it as being a love letter from the protagonist because it has no signature.[9] Alphys reluctantly goes on a date to the garbage dump with the protagonist. After Alphys hides, Undyne sees the protagonist at the dump and asks for her letter back; she wants to give it to Alphys herself. After Undyne walks away, Alphys expresses regret about her lying to Undyne, and the protagonist suggests a roleplay to help Alphys express her feelings.[10] Undyne interrupts the roleplay, and Alphys tells her about her romantic interest. Undyne reciprocates these feelings and tosses Alphys into the trashcan.[11]

Undyne says that Alphys needs to work on her self-image,[12] and Papyrus leaves with Alphys to help with her emotional transformation. After the two leave, Undyne asks the protagonist if anime is real or not and thanks them for helping with Alphys.

Later on, Undyne interrupts Asgore's encounter with the protagonist and demands that they befriend one another. Alphys and Undyne almost kiss before Flowey's ambush, but Toriel chastises them for kissing in front of a child. Flowey ensnares the protagonist's friends with a Photoshop Flowey vine, and Undyne protects them from incoming attacks from Flowey. He then absorbs the six human SOULs and most of the SOULs of the monsters in the Underground.


When the protagonist talks to Undyne in the epilogue, Undyne states that she is glad that she lost to the protagonist and then resolves to watch anime with Alphys. The Royal Guard is disbanded. Toriel also texts the protagonist that Undyne was able to lift Asgore, Sans, Papyrus, Alphys, and Toriel herself at once, but was uncertain as to how to put them down.

On the surface, Undyne pursues Papyrus after he runs off to meet more humans. In the True Pacifist Ending Credits, Undyne kisses Alphys and laughs after she faints.

Genocide Route

You're gonna have to try a little harder than THAT.

— Undyne the Undying

After the protagonist attacks the Monster Kid, Undyne protects them and takes the blow instead. Even though her HP reduces to zero, Undyne holds on through Determination and reforms into Undyne the Undying.[13] If the protagonist defeats her, she tells them that Alphys was watching their battle and has evacuated the rest of the monsters to safety.[14] Undyne begins melting due to her Determination and then turns to dust.

In Battle

For an in-battle description, see Undyne/In Battle.



Alphys and Undyne have crushes on one another. Undyne first met Alphys in the Garbage Dump, listening for hours about where she thought the abyss there led. The two became close friends soon after, with Alphys introducing her to anime at some point. They hang out often, and Alphys uses the seagrass throughout Waterfall to make a special frosty treat for Undyne.[15] Alphys and Undyne also worked together to create some of the puzzles in Waterfall.[16]

They nearly kiss in the True Pacifist Route, but Toriel interrupts them and tells them not to kiss in front of the protagonist.


Undyne thinks of Papyrus as a close friend. She is impressed by his persistence and trains him in cooking, but is concerned about his well-being and secretly does not want him to join the Royal Guard because she believes that he is too nice to fight.[17] She teaches him how to cook in hopes that he changes his mind about joining the Royal Guard. Undyne sometimes enjoys messing with Papyrus,[18] but she often forgets that he usually takes things literally.[19] She is heartbroken and infuriated if the protagonist kills Papyrus during a Neutral/Genocide Route.

The Protagonist

Undyne initially despises the protagonist and believes that they would be more useful dead than alive.[20] If the protagonist spares her and offers her water in Hotland, she begrudgingly befriends them if they have earned no EXP. Though Papyrus tricks Undyne into befriending the protagonist, she genuinely cares about them at the end of their date.

If the protagonist earned no EXP and befriended Undyne in a previous route, she remembers them as a friend but brushes off the feeling before her battle.[21]


Even though Asgore is her boss, Undyne sees him as a friend and knows his favorite type of tea. When she was younger, Undyne challenged Asgore to a fight but could not land a single blow on him.[22] She was humiliated because he did not fight back and only dodged her attacks. Asgore then offered to train Undyne and eventually promoted her to head of the Royal Guard.

After Toriel fireballs Asgore in the True Pacifist Route, Undyne consoles him because he is crying.[23]


They live in the same neighborhood. They are intimidated by her,[24] but she tries to be a good neighbor to them. She seems concerned about them being alone after their cousin left and tells the protagonist to be nice to them.[25]


Undyne does not know that Mettaton is Napstablook's cousin. She has a distaste for him,[26] and she does not like his show.[27] Though she does acknowledge that she "admires his lifestyle."[26]


Undyne used to give her piano lessons,[28] but one day she stopped coming – probably after her sister fell down.



  • "Undyne" derives from "Undine," a womanly water nymph from Greek lore. It is also a play on "undying," as Undyne does not die when reduced to zero health before her battle on a Genocide Route.
    • When attempting to name the fallen human "Undyne," the response becomes "Get your OWN name!" and prevents the name from being used.
  • If either Snowdrake, any or all of the canine members of the Royal Guard in Snowdin or Shyren is killed, Undyne will comment on it on her pre-battle monologue.
    • Papyrus's death supersedes all other pre-battle dialogue and changes her speech the most.
  • Despite donning a helmet during the moment, Undyne's face appears in the dialogue box before her battle as if she had already removed her helmet. If the protagonist approaches to fight Undyne, she appears without her helmet.
  • When Undyne was younger, she followed Gerson around to watch him beat up bad guys, much like how Monster Kid follows Undyne. However, whenever Undyne tried to help Gerson fight bad guys, she ended up attacking "the mailman or something like that."[29]
  • Undyne is consistently shown to be right-handed. However, after scoping the protagonist after Papyrus's report, she handles her spear in her left hand.
  • Despite having an eye patch in her left eye, she doesn't seem to have an eye patch when she turns left.
  • When Undyne says "En Guarde!" before her fight with the protagonist begins, the sentence is misspelled. The right spelling being "en garde," as the sentence is in French. This could also be a combination of the French and English spelling, Garde, and Guard, giving Guarde.
  • While in Undyne's house for the befriending scene, the table that the protagonist sits at is decorated with a doily. The doily cracks along with the table after Undyne throws a spear at it.
  • Undyne the Undying is the only Genocide Route specific boss that does not die in one hit.
    • However, when she jumps in the way of Monster Kid when the protagonist attempts to kill them, she takes more damage than she has HP. This does not kill her, however.
  • Undyne is the only character that recognizes Toriel as Asgore's ex-wife.
  • In Undyne's faux battle, she has one more defense point than in her actual battle, despite being unarmored.
  • Undyne is the only character to have "special" normal attacks. All of her Green Mode spears are either white and blue or yellow but behave the same as white attacks. Also, her spear she throws when doing a green to red switch is white and blue and has a shadow.
  • If the protagonist attempts to kill Undyne on a Neutral Route, they will notice that Undyne's name overlaps the health bar at one point.
  • There's a glitch where if the protagonist is standing as far to left as possible while initiating Undyne's monolgue, they can be shot very high up. The protagonist can then enter the cave, effectively postponing the first fight.
    • If you decide not to enter the cave and enter the battle normally, the protagonist will still be able to move in the air, but Undyne will pursue on the bridge heading to Art Club Room in Hotland.
  • Undyne and Toriel are the only Bosses that the protagonist can flee from during a battle on a Neutral Route.
    • However, You can only flee Undyne's battle if the protagonist' SOUL is red.
  • If Undyne jumps off the cliff to save Monster Kid, her HP is lowered in the following battle.
    • According to Toby, he wanted her armor to be cracked too, but he forgot to add it.[30]


  1. Undertale (6 October 2015). "how is undyne's name pronounced?"
  3. "I don't actually want to hurt you either. At first, I hated your stupid saccharine schtick, but... The way you hit me right now, it... Reminded me of someone I used to train with." - Undyne
  5. "I've READ Alphys's human history book collection! I know all about your giant swords... Your colossal, alien-fighting robots... Your supernatural princesses..." - Undyne
  6. "That's where I first talked to you! Weren't you SUPER terrified? I practice that monologue ALL the time in the mirror!" - Undyne
  7. Going off-the-cuff... It helped that I... Uh. Completely forgot the words to my monologue, anyway..." - Undyne
  8. "Why would I EVER be friends with YOU!? If you weren't my houseguest, I'd beat you up right now!" - Undyne
  9. "Oh My God? Did YOU write this letter? It wasn't signed, so, I had no idea who could have..." - Alphys
  10. "NGAHHHH!!! NGAHHH!!!! I'M UNDYNE AND I'M PILING ON THE SMOOCHES!!!" - Alphys roleplaying as Undyne
  11. "What I like about you is that you're PASSIONATE! You're ANALYTICAL!! It doesn't matter what it is! YOU CARE ABOUT IT!!" - Undyne
  12. "Alphys... I want to help you become happy with who you are!" - Undyne
  13. "Deep, deep in my soul. There's a burning feeling I can't describe. A burning feeling that WON'T let me die." - Undyne
  14. "Alphys told me that she would watch me fight you... And if anything went wrong, she would... evacuate everyone." - Undyne
  15. "Ugh, ice cream!? Sugary... COLD... Talk about GROSS. Now this chilly pink stuff that Alphys makes me..." - Undyne
  16. "Alphys helped measure out the mud tiles for this puzzle. It was a lot of work, but we got to make sand castles after." - Undyne
  17. "But, um, to be honest... ...I don't know if I can ever let Papyrus into the Royal Guard. Don't tell him I said that! He's just... well... I mean it's not that he's weak. He's actually pretty freaking tough! It's just that... he's... he's too innocent and nice!!! I mean, look, he was SUPPOSED to capture you... and he ended up being friends with you instead! I could NEVER send him to battle! He'd get ripped into little smiling shreds." - Undyne
  19. "Papyrus, wait, you know I'm joking, right...?" - Undyne
  20. "You know what would be more valuable to everyone? IF YOU WERE DEAD!!!" - Undyne
  21. "The whole time I was chasing after you... I felt something... Strange. The echoes of something warm, something... Something like 'I miss being friends with you.'" - Undyne
  22. "Y'know, I was a pretty hotheaded kid. Once, to prove I was the strongest, I tried to fight ASGORE. Emphasis on TRIED. I couldn't land a single blow on him!" - Undyne
  23. "Hey ASGORE, is that your ex? Jeez. That's rough, buddy." - Undyne
  24. "hmmm... i should probably try to make friends with my neighbor. she's kind of scary, but i feel like i'm always too late to make friends..." - Napstablook
  25. "Be nice to them, okay!? Cherish this ghost!!!" - Undyne
  26. 26.0 26.1 "All he did was lie seductively on the piano... And fed himself grapes. I don't really like that guy. But I admire his lifestyle." - Undyne
  28. "Oh yeah, Shyren lives around here. I used to give her piano lessons." - Undyne
  29. "When she was younger, Undyne would follow me around, to watch me beat up bad guys... Sometimes she'd even try to help! Though, most of the time the folks she attacked weren't bad guys. It'd be the mailman or something like that." - Gerson
  30. "If Undyne jumps off the cliff to save Monster Kid, when you fight her, her HP's lowered. I wanted to have her armor cracked too but I forgot" -Toby Fox. June 13, 2016. Twitter.

Main Characters Flowey ● Toriel ● Sans ● Papyrus ● Undyne ● Alphys ● Mettaton ● Asgore Dreemurr ● Frisk ● Chara
Ruins Enemies Dummy ● Froggit ● Whimsun ● Moldsmal ● Loox ● Vegetoid ● Migosp ● Napstablook
Snowdin Enemies Snowdrake ● Chilldrake ● Ice Cap ● Gyftrot ● Doggo
Dogamy and Dogaressa ● Lesser Dog ● Greater Dog ● Jerry ● Glyde
Waterfall Enemies Aaron ● Moldbygg ● Woshua ● Temmie ● Mad Dummy ● Shyren
Hotland Enemies Vulkin ● Tsunderplane ● Pyrope ● Muffet ● Royal Guards ● So Sorry
CORE Enemies Final Froggit ● Whimsalot ● Astigmatism ● Madjick ● Knight Knight
Amalgamates Memoryhead ● Endogeny ● Reaper Bird ● Lemon Bread ● Snowdrake's Mother
Hard Mode-only enemies Parsnik ● Moldessa ● Migospel
Vendors Nice Cream Guy ● Snowdin Shopkeeper ● Gerson ● Tem Shop ● Bratty and Catty ● Burgerpants
Other Characters NPCs ● Monster Kid ● Annoying Dog ● River Person ● Eight Humans ● Asriel Dreemurr
W. D. Gaster ● Lost Souls

cs:Undyne de:Undyne es:Undyne fr:Undyne ja:Undyne pl:Undyne pt-br:Undyne ru:Андайн uk:Андайн zh:Undyne