Sans- Sans is a pun loving, friendly skeleton who unlike most monsters won’t fight you or try to take your soul due to a promise he made to a friend. He is the older brother of Papyrus.

Papyrus- papyrus is a tall skeleton who loves puzzles and dreams of becoming a member of the royal guard. He will fight you but will not kill you in order to capture you and gain entry to the royal guard. He is the brother to sans and best friend to Undyne.

Undyne- undyne is the captain of the royal guard who dreams of obtaining the last human soul in order to break the barrier and free all monsters. Due to this dream, she will chase you through the waterfall area relentlessly and lash out after you to obtain your soul. Her best friend is papyrus and she is secretly in love with the royal scientist Alphys.

Alphys- Alphys is the royal scientist in the underground. She is a anime loving lizard like creature that will instead of fighting help you get past her robot creation mettaton. she has a secret love for Undyne.

Mettaton- Mettaton is Alphys robot creation that is a tv star in the underground. he will start off as a sqare robot that will try to kill you through multiple forms of tv shows that involve a time trial, a musical, and a cooking show but when confronted for the final time will become Mettaton ex.

Mettaton EX' Mettaton EX is the transofmation of Mettaton that you activate when you trick him into turning around and then flipping the switch on his back. this transformation is much differant from his original form including legs, a face, a body, and a much more flashey personality. he is obsessed with beuty and will make your death "Absolutely Beutiful".

Asgore- Asgore is the king of all monsters and the EX husband of Toriel. He is mostly peaceful but will fight you for your soul in a fight where he gets rid of your mercy button, forcing you to fight.

Toriel- Toriel is the ex wife of asgore and is a goat mother who locked herself in the ruins to hopefully save any children who might fall there. she is a kind soul who loves baking and children.

Asriel- Asriel is the son of Toriel and Asgore and the soul tarpped inside of flowey. He is kind but due to being a flower his anger made him want to become a god and destroy the timeline.

Flowey- Flowey is the flower form of asriel that became this after he died. He hates the world and constantly wants genocide and to end all monsters as well as humans.