A goat-like boss monster covered in white fur, featuring drooping ears, short horns, fangs, and long eyelashes. While she can be overprotective, she is deeply kind—a personification of motherhood. She acts as a guardian to help those who fall into the Underground to the best of her ability. Asgore's ex-wife. First person: I (polite/feminine) Second person: you / my child / personal name

A ghost monster with a classic sheet-like appearance and a slightly translucent body. Occasionally seen wearing headphones. Possesses a very gloomy personality, being introverted with low self-esteem. They are polite and considerate of others, often blaming themselves for things. Mettaton calls them "Blooky." First person: I (soft/polite) Second person: you (soft) / personal name

A skeleton monster wearing a blue hoodie over a white shirt, black shorts, and light pink slippers. He has black eye sockets with white pupils; during combat, his left eye may glow yellow and cyan. Generally lacks motivation for anything, often seen dozing off at his sentry station or taking breaks away from his post. Papyrus's older brother. First person: I (casual/slangy) Second person: you (blunt) / you (casual) / personal name

A skeleton monster wearing a red scarf, boots, gloves, and blue trunks. A friendly and kind soul who dreams of making friends with a human. He is extremely determined and even visited Undyne's house to beg to join the Royal Guard. First person: The Great I (boastful) Second person: you (rude/archaic) / Guest / personal name

A fish-like monster with blue skin, sharp fangs, and an eyepatch over her left eye. Her ears are shaped like fins, and she ties her red hair back in a ponytail. Possesses a strong will but a fierce temper, showing no mercy to those she deems enemies. She is deeply loyal to her friends and has a strong sense of responsibility. Head of the Royal Guard. First person: I (tomboyish/tough) Second person: you (rude/archaic) / you (blunt) / personal name

A reptilian monster with a plump build and orange-yellow scales, wearing glasses and a plain white lab coat. A shy, nerdy shut-in. A researcher who loves anime and manga and has a habit of stuttering. She harbors a secret crush on Undyne. First person: I (polite/formal) Second person: you / Guest / personal name

A humanoid robot with long black hair covering his right eye. His pink chest features a speaker and a dial, with a heart-shaped core housed in his torso below. He wears black leggings and pink boots with heels. A robot built by Alphys and the star of the Underground, equipped with anti-human functions. Napstablook's cousin. First person: I (polite/showy) Second person: you (soft) / little kitten / darling / personal name

A beast monster with golden hair and a beard, and two large curved horns. He wears armor, a purple cloak with golden shoulder guards, and a crown. Kind and easygoing. Respected by the monsters as a wonderful king. Toriel's ex-husband. First person: I (polite/formal) Second person: you (soft) / personal name