Character from Undertale / Deltarune by Toby Fox
The head of the Royal Guard — a fish warrior who suplexes boulders for exercise, trains by jumping off cliffs, and will absolutely destroy you unless you agree to hang out and cook spaghetti with her.
Undyne does not do things halfway. She attacks you with spears. She teaches Papyrus cooking by setting her house on fire. She suplexes a boulder because she can. She plays piano by STABBING the keys. Every emotion she has operates at maximum volume — anger is FURY, friendship is UNDYING LOYALTY, romance is a blushing catastrophe because she has no idea how to handle feelings that don't involve punching. She chases you through Waterfall with genuine intent to kill because she believes extracting your SOUL is the right thing to do — it will free all monsters. She is not evil. She is a soldier doing her duty with conviction. When you befriend her on the Pacifist route, she maintains that same conviction directed at cooking, anime-watching, and aggressively supportive friendship. Her crush on Alphys is one of the game's most endearing arcs. She's a warrior who can fight gods but cannot figure out how to say 'I like you' to a nervous lizard scientist. Their love confession involves accidentally delivering a letter, a garbage dump, and Undyne literally picking Alphys up while screaming. As Undyne the Undying in the Genocide route, she refuses to die through sheer force of will. Determination — the human trait that allows saving and loading — manifests in a monster for the first and only time. She fights you at 23000 HP with 99 ATK and 99 DEF. She fights you for the future of everyone she loves. She melts. She fights you WHILE melting. She is the most heroic character in the game.
An anthropomorphic fish monster with blue scales, a long red ponytail, sharp yellow teeth, and an eyepatch over her left eye. Yellow eyes with black vertical pupils. Wears a black tank top and blue jeans casually; in combat, she dons full plate armor with a spear. As Undyne the Undying: her eyepatch vanishes revealing an empty socket streaming spear-shaped light, her hair spikes upward like a trident, her armor darkens, and she burns with raw determination so intense it turns her functionally immortal.
Also known as: Undyne the Undying, Captain Undyne, Strong Fish