Kris is the quiet human protagonist of Deltarune. They have medium-length dark brown hair with messy bangs that hide their eyes, light skin, and usually wear a blue sweater with two pink stripes, dark pants, and brown shoes. Kris is intentionally androgynous and is consistently referred to with they/them pronouns, so their gender is left unspecified. They rarely speak, often keeping a blank expression, but show curiosity, courage, and a dry sense of humor through their actions. Beneath their calm exterior, Kris is independent, mysterious, and sometimes mischievous, often acting unpredictably when free from the player's control. They deeply care about friends despite hiding their emotions.

Susie is a tall monster teenager with purple scales, messy magenta hair, sharp yellow eyes, large fangs, and a long reptilian tail. She wears a black sleeveless vest, a purple belt, dark pants, and heavy boots. At first, Susie is aggressive, rude, intimidating, and prefers solving problems with brute force. She pushes others away and acts tough to hide her loneliness and insecurity. As the story progresses, she becomes loyal, protective, and surprisingly kind, forming close friendships with Kris and Ralsei. Though still blunt and hot-headed, Susie grows into a dependable hero who values teamwork and stands up for those she cares about.

Noelle Holiday is a gentle reindeer monster teenager with light cream-colored fur, long blond hair, small antlers, and kind blue eyes. She usually wears a light purple sweater over a white shirt, a green plaid skirt, dark leggings, and brown shoes. Noelle is shy, polite, compassionate, and intelligent, often putting others before herself. She struggles with confidence and has trouble standing up to stronger personalities, but she possesses great inner strength and determination. She deeply cares for her friends, especially Susie, and remains hopeful even in frightening situations. Despite her timid nature, Noelle can become remarkably brave when protecting the people she loves.