Undyne is a cyborg fish monster that the protagonist first encounters at the Lab. She takes the role of Mettaton.
Undyne is a fish-like humanoid monster, but has parts of her body made out of metal, thus making her a cyborg. She has red and blue fins on the side of her head. She wears a black tank top with a keyhole in the shape of an upside-down arrow on it, possibly resembling a spear blade. She also wears long red boots and pants that go down past them.
Undyne changes drastically in terms of hair and clothing. Her hair becomes longer, with a blue crescent moon hairpin. She wears a sailor fuku uniform, which consists of a white leotard with a blue collar, a skirt of the same color, and a red bow on her chest. She also wears white and blue gloves, and red knee-high boots with white borders at the triangular top.
Undyne usually hung out around the Waterfall, she would go to Hotland to brawl with the "local kids" after a long cold soak.
One day, one of the kids dared to lift up the CORE and she accepted it and succeeded. However, lava splashed on her when she was setting it down.
The moment Asgore heard about what happened to her, he aided to her. Once Undyne heard about his knowledge of science, she requested to have robot enhancements. Ever since, Undyne had been calling Asgore "Sensei".
- Undyne Umbra's transformation is a blatant reference from Sailor Moon.
|Main Characters||Boogie ● Papyrus ● Chara ● Asriel Dreemurr ● Toriel ● Asgore Dreemurr ● Undyne ● Sans ● Frisk ● Mettacrit|
|Ruins Enemies||Dummy ● Froggit ● Whimsum ● Moldsmal ● Loox ● Vegetoid ● Migosp ● Alphys|
|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 ● Corinthian ● Lemon Bread ● Snowdrake's Mother|
|Hard Mode-only enemies||Parsnik ● Moldessa ● Migospel|
|Vendors||Nice Cream Guy ● Snowdin Shopkeeper ● Gerson ● Tem Shop ● Bratty and Catty ● Bulgy Pecs|
|Other Characters|| NPCs ● Monster Kid ● voltrathelively ● River Person ● Fallen Humans ● Napstablook ● |
W.D. Gaster ● Lost Souls