Scooby-Doo and the Ghoul School

A group of girls who are the offspring of famous horror monsters, who unlike them are not wholly villainous.

• Miss Grimwood - The middle-aged headmistress of the school. She wears a red cape over a pink dress, a red headband, red shoes, and has short black hair. She has a pet dragon named Matches.
• Matches - A small, light-green dragon who serves as Miss Grimwoods's pet guard dog. He often gets duties like heating food in the kitchen or warming up items with his fire breath in which his body will turn a dark red color. However, he is not able to breathe fire when his body is wet. Matches often shows a bad temper. At first, he shows a strong dislike towards Scooby—a recurring gag throughout the film is that Scooby would make Matches angry and get his tail set on fire as punishment. Matches later warms up to Scooby after the dog saves him from the Grim Creeper and helps rescue the girls from Revolta.
• Sibella - Count Dracula's daughter. She has green eyes, light purple skin, purple hair, red shoes, and a dark purple dress with a red belt. Sibella can turn into a bat at will, which she uses for a variety of different reasons such as rescuing or looking for people, or for simple things such as delivering a pizza. Unlike traditional vampires like her father, she is immune to sunlight and can go out during the day. She is also shown to be the most strongly willed of the five Grimwood girls—she is the last to undergo Revolta's hypnosis spell and tries to fight back. She often uses phrases with vampire-related puns such as "fangtastic" and "You bat" (you bet). She is talented at making bat-robes (bathrobes) and dragon fire-proof robes as seen when she gives her father and Matches each one.
• Elsa Frankenteen - The daughter of Frankenstein's monster. Elsa has platform-like brown sandals and a green dress with a light green T-shirt underneath. She can endure electric shocks and her black hair is standing up above her head thus resembling the Bride of Frankenstein. She presents her father with a portable shockman that has a rechargeable battery-pack that lasts for weeks, showing that her father can also endure electric shocks. She is the tallest and the strongest of the girls. She has a deeper voice which is more masculine-sounding than the other four girl ghouls.
• Winnie - The daughter of the Wolfman. Quite often Winnie howls before making a statement and unlike common stereotypical werewolves like her father, she does not turn back into a human during daylight hours. She wears a blue dress and a light blue bow-tie, and has light brown fur, yellow eyes and orange, curly hair. Winnie makes a juicer as her father's Halloween gift, which makes bitter lemonade, something her father enjoys. Out of the rest of the girls, she is the most talkative and can also be very loud and somewhat competitive.
• Phantasma - The Phantom's ghostly daughter. Everyone calls her "Phanty" for short. With a shrill, high laugh, she has short white hair with a blue streak and pale blue skin. She wears a blue dress and white boots. Being intangible, she can float through walls and doors. She has a good sense of humor and is musically gifted, also displaying a great love and appreciation for music. Phanty's gift to her father is her latest composition which was called "Duet For Three Hands and Six Tentacles".
• Tanis - The Mummy's daughter, Tanis is the smallest and youngest of the girls. She has big, blue eyes and a bandage ponytail embellished with a dark pink bow. She usually gets tangled in her bandages and the others have to untangle her and re-wrap her. She calls her daddy "Mummy Daddy." Tanis has an Egyptian trophy case in which to store trophies, but she often gets worried when it looks like they are going to lose a game. Tanis gave her father a fright-light to brighten the darkest mummy case for a present. She is a shy sweetheart, and is the most nervous out of the group of girls. Even Scooby warms up to her immediately, mostly because of her innocence. She often sucks on her thumb to show her innocence.

In the final scene of the film, the daughters of an alien, the Creature from the Black Lagoon, and Godzilla come to attend but Shaggy, Scooby and Scrappy drive off before meeting them.

A group of boys of Colonel Calloway's Military School, located next to Grimwood. They often use the terms "affirmative" or "negative" when agreeing or disagreeing with particular happenings.

• Colonel Calloway - The head of Calloway Military School. Fair yet very stern, Calloway seems to have a reciprocated attraction to Miss Grimwood.
• Tug Roper - The leader of the cadets. He often tries to maintain his dignity and even resorts to cheating during the volleyball game against the Grimwood Girls, but he and his team still lose. He does what he can to impress the colonel, but often disappoints him with his clumsiness.
• Miguel - The inventor of the group, most of the time his inventions are messed up by the others.
• Jamal Williams - The tallest and most skilled of the cadets, despite not being the leader, Col. Calloway seems to admire him more than Roper; he always answers to every positive sentence with "affirmative".
• Grunt - The largest member of the cadets; despite being overweight, he is very athletic and very strong.
• Baxter - The smallest member of the group. He seems to be the most obedient of the cadets; following the colonel's every word and acknowledging him at almost every time.

• Revolta - The Witch of the Web. She plans to make the students at the ghoul school part of her evil squad permanently as part of her plans to take over the world. In addition, she claims that their parents have "gone soft." Her main magic is mind control via spider bats who put web-like hypnosis headphones on the victim and Revolta issues commands through that headphone which hypnotizes the victims. She is also a good potions maker and can brew potions that make others evil permanently.
• Grim Creeper - Revolta's assistant. He looks like a green, overgrown pumpkin with long vines for limbs and one eye in the middle of his head. He unsuccessfully tried to get the wand for Revolta when Matches came near him.
• Mirror Monster - A monster who lives in one of Revolta's mirrors and can change into anyone that looks into it. In the movie, the monster traps Shaggy inside the mirror and replaces him. He chases after Scooby, who eventually fools him into thinking he is one of Revolta's slaves. In the end, Matches burns his backside, and he jumps back into the mirror, setting Shaggy free.