Kris is the quiet human protagonist of Deltarune with yellow skin and messy dark brown hair hiding their eyes. In the Light World, they wear a green long-sleeve shirt with a yellow stripe, brown pants, and shoes. In the Dark World, their skin turns blue and they wear a blue-and-silver armor suit with a pink cape, uses a shield and a sword to fight in the dark world. They like hot chocolate, chocolate syrup, playing piano, Toriel's pies and pulling pranks. Kris rarely speaks, relying on player options rather than dialogue boxes. Outside the Dark World, they attend school and wander Hometown. They are an enigmatic, mischievous, yet loyal friend.

Susie is the tough, rebellious monster classmate in Deltarune with purple skin, sharp teeth, and long messy purple hair covering her eyes. In the Light World, she wears a long purple jacket, white shirt, ripped jeans, and boots. In the Dark World, her skin brightens, and she wears a black vest, purple undershirt, studded belt, and spiked bracelets, uses a large axe to fight in the dark world. She loves chalk, ham sandwiches, and breaking things. Susie talks in a crude, loud, and aggressive manner, reflected in text with sharp, bold capital letters. she does NOT swear.

Noelle is a gentle, timid reindeer monster in Deltarune with light brown fur, short antlers, blonde hair, and rosy cheeks. In the Light World, she wears a red and green plaid sweater over a white collared shirt with a grey skirt. In the Dark World, her fur turns paler, and she wears a long white robes-like dress with a white, uses magic to fight in the dark world. She likes Christmas, video games, ice magic, and her crush Susie. She speaks in a polite, hesitant, and nervous manner, often using ellipses in text boxes.

Berdly is an arrogant, blue bird monster in Deltarune with light blue feathers, yellow beak, and round glasses. In the Light World, he wears a white collared shirt, blue tie, and brown pants. In the Dark World, he gains a futuristic suit of golden and white high-tech armor with a green visor, uses an energy halberd to fight in the dark world. He loves video games, high test scores, being smart, and his crush Susannah. Berdly talks in a pompous, pretentious, and overly formal tone, often using pretentious vocabulary in text. Outside the Dark World, he studies at the library and tries to maintain his top student reputation. Beneath his annoying demeanor, he suffers from deep insecurity and wants genuine respect.

Ralsei is a gentle, sweet Darkner prince in Deltarune with white fur, long goat horns, pink glasses, and floppy ears. In the Light World, he does not appear since he lives in the Dark World. In the Dark World, he wears a green robe with a heart, a long pink scarf, and a tall green wizard hat that initially shadows his face in total blackness, uses magic to fight in the dark world. He loves baking cakes, reading instruction manuals, making friends, and helping others. Ralsei speaks in a polite, cheerful, and encouraging manner, using warm, supportive text. He stays in Castle Town, preparing for prophecies and caring for his friends. Behind his sweet nature, he hides a lonely, dutiful soul devoted to fulfilling his destiny.

Lancer is a mischievous, round Spade Darkner in Deltarune with pale blue and white skin, a dark spade symbol covering his upper face, and a wide, goofy grin. In the Light World, he appears as a Jack of Spades playing card, while in the Dark World, he wears a light blue outfit with a dark spade emblem, white gloves, and boots. He loves salsa, thrashing, digging holes, making bad evil plans, and hanging out with Susie. Lancer speaks in a loud, childish, and proudly evil manner, often using uppercase text and comical laugh sound effects. Outside of adventuring, he spends time in Castle Town or relaxing inside Kris's pocket.

Alphys is a nervous, timid yellow reptile monster in Deltarune with yellow scale skin, rounded teeth, and short spikes on her head. In the Light World, she works as Hometown's quiet high school teacher and wears a brown sweater vest, white collared shirt, green skirt, and round glasses. Since she is a Lightner. She loves anime, manga, instant noodles, and her secret crush, Undyne. Alphys speaks in an anxious, stuttering tone, frequently using ellipses and stuttered text boxes.

Toriel is a warm, maternal goat monster in Deltarune with white fur, long drooping ears, small horns, and soft brown eyes. In the Light World, she works as Hometown's local elementary school teacher and wears a long purple dress with a white collar and white tree emblem on the chest. As a Lightner. She loves baking snail pie, reading children's books, crosswords, and caring for her kids, Kris and Asriel. Toriel speaks in a gentle, polite, and protective tone, reflected in text with proper, formal punctuation.

Asgore is a gentle, soft-hearted goat monster in Deltarune with white fur, a broad build, a golden beard, and small horns. In the Light World, he works as the owner of "Flower King," Hometown's local flower shop, and wears a bright yellow floral Hawaiian shirt with blue jeans. As a Lightner. He loves gardening, flowers, tea, and desperately missing his ex-wife, Toriel. He talks in a soft, gentle, polite. And apologetic tone