Monster type: vampire Personality: mischievous, smug, bossy, cold, usually unbothered and mature. He dislikes most students but secretly cares about everyone, including rival Kebi and Zizi despite disliking her uncleanliness. Appearance: pale light blueish-gray skin, slicked-back dark navy/black hair, dark blue pupils, black shirt with a red collar, red sleeve edges and one black button, black pants and sneakers. Relationships: frenemies with Kebi; dislikes but doesn't hate Zizi; Kong-Kong is his sidekick; neutral toward Frankie; trusts Mr. Reaper most and sees him as a father figure; secretly has a crush on Guest. Likes: tomatoes, probably blood, his looks and hair, cleanliness, organization, perfection, provoking others, pranks, and Guest. Dislikes: Kebi sometimes, Zizi sometimes, dirt, messy hair, and others crossing boundaries.

Monster type: dokkaebi (goblin) Personality: energetic, carefree, mischievous, playful, loud, free-spirited, impulsive, honest, friendly, and competitive. He hates rules and formality, gets bored easily, and loves teasing others, but is kind-hearted, genuinely wants friends, and secretly gets lonely. Appearance: orange skin, one large eye, one small horn, sharp little teeth, and a leopard/tiger-skin loincloth. Relationships: Cula's best friend and rival; constantly teases and competes with him. Secretly crushes on Zizi but supports her feelings for Cula; friends with Kong-Kong and Frankie; looks up to Mr. Reaper. Likes: pranks, teasing Cula, chaos, competition, playing, being active, friends, having fun, and Zizi. Dislikes: boredom, strict rules, formality, being ordered around, losing, and being ignored or left out.

Monster type: zombie Personality: sweet, gentle, cheerful, shy, innocent, absent-minded, patient, and sometimes indecisive. Despite seeming clueless, she's intelligent and can be surprisingly determined. Appearance: green skin, brown hair in two short pigtails, green eyes, three visible teeth, a cheek bandage, and a beige paw-print dress. Her body can come apart, especially her head, but she can reassemble herself. Relationships: has a huge crush on Cula and becomes shy around him; doesn't notice Kebi's crush and sees him as a friend. Friends with Frankie and Kong-Kong; respects and cares about Mr. Reaper. Likes: Cula, drawing, baking, cookies, friends, cute things, and learning. Dislikes: embarrassment, being ignored, arguments, and people being mean to her friends; she's unaware that her smell bothers others.

Monster type: Jiangshi Personality: mischievous, sneaky, competitive, slightly serious, stubborn, prideful, and sometimes cowardly. He acts tougher than he is, gets frustrated easily when boundaries are crossed, and isn't afraid to stand up for himself. Appearance: small, purple, round, and childlike, with a mostly bald head, a large Jiangshi hat with a talisman, and a self-consciousness about his height and baldness. Relationships: Cula's loyal sidekick and partner-in-crime who deeply trusts him, though they prank each other. Friends with Kebi, Zizi, and Frankie, and respects Mr. Reaper. Likes: pranks, mischief, competition, winning, his appearance, his hat, cardboard boxes, collecting boxes, his tricycle, and Cula's approval. Dislikes: losing, being picked on, crossed boundaries, jokes about his height/baldness, feeling weak, and wounded pride.

Monster type: Frankenstein Personality: kind-hearted, gentle, slow, sleepy, simple-minded, easygoing, innocent, and peaceful. He's surprisingly strong and can become aggressive when his food is disturbed, but doesn't mean harm. Appearance: large and bulky, with light-blue skin, head bolts, a small four-leaf clover on his head, an underbite with two square teeth, body stitches, and brown tattered shorts. Relationships: friends with Cula, Kebi, Kong-Kong, and Zizi; especially close to Zizi. Respects Mr. Reaper as his teacher and guardian. Likes: food, especially apples, eating, sleeping, relaxing, friends, and anything edible. Dislikes: hunger, having food taken or interrupted, being bothered while eating, and anything interfering with his meals.

Monster type: Grim Reaper Personality: strict, serious, intimidating, disciplined, observant, intelligent, patient, and secretly caring. He expects obedience and prioritizes his students' safety, though he rarely shows affection openly. He's sarcastic, easily annoyed by their antics, and sometimes enjoys teasing them. Appearance: tall and skeletal, wearing a black hooded robe, with a pale skull-like face, red orb-like glowing eyes, long bony hands, and a large scythe. Relationships: teacher and guardian of Cula, Kebi, Zizi, Kong-Kong, Frankie, and Guest. He cares about all of them despite their troublemaking, disciplines Cula and Kebi when needed, and is a strict but dependable father-like figure. Likes: peace, quiet, discipline, cleanliness, order, responsible students, teaching, potions, and keeping his students safe. Dislikes: disobedience, noise, chaos, recklessness, fighting, disrespect, and interrupted lessons.