Toriel is the second major character the protagonist meets. She saves the protagonist from Flowey and guides them through the Ruins, wishing to protect and to teach them to avoid the dangers of the Underground. Toriel is the former Queen of the monsters, the ex-wife of Asgore, the mother of Asriel, the adoptive mother of the first human, and the first boss, as she guards the Ruins exit.

Toriel is a Boss Monster whose head resembles a white-furred Nubian Goat, structured with floppy ears and tiny horns. She has a pair of visible fangs and long eyelashes, and her irises have a dark red tint. She has an anthropomorphic body, with paws at the end of her limbs. She wears a long purple robe with white sleeves and the Delta Rune on the chest. Toriel can also be seen with reading glasses, when reading a book on snail facts.

Toriel is a kind monster that acts as a protective mother figure for the protagonist. She is sincere in expressing her love through words and actions, such as when she was married to Asgore. She employs tough love on the protagonist and Asgore. Toriel cares for children and was excited to become a mother.