"Undyne 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 tank top and jeans. Her eyes have black vertical pupils and a yellow sclera. Undyne has no nose. Undyne is passionate about everything that she does. She acts quickly on her ideas and is steadfast in her beliefs." Undertale Wiki.

Has a confident and loud voice.

Assigned voice: Marceline from Adventure Time or Jasper from Steven Universe