- Main article: Casper the Friendly Ghost
Casper is an oddity to the school, serves as a main protagonist; He is a Ghost who is friendly and kind. He lives with his three uncles, Stretch, Stinkie, and Fatso. In Scare School, Casper's closest best friends are Mantha, an independent Zombie girl, Ra, a cool Mummy who he loves like a family . And he continuously faces the oppressions of Thatch, a vampire bully and the Headmasters, Alder & Dash.
A mummy far away from his tomb but he fits in at Scare School. He is more than 2000 years old (in one episode of the series he celebrates his 2500th birthday) and is royalty. Ra also once disobeyed his parents and forged his father's signature on a permission slip to go with his friends on a camping trip. He was caught but his parents allowed him to stay in Scare School. Another time, Ra, with Casper's help, showed off in front of students, making him popular, which went to his head. Thatch dared him to make a jump over the Abyss of Souls, but he didn't go through it and admitted to being a fake. In the episode Curse of the Sandwich it is revealed that Ra can also be quit gullible. Throughout the episode Ra was convince that he was turning into a vampire after accidentally taking a bite out of Thatch's sandwich despite Casper and Mantha telling him he wasn't. When Thatch overheard Mantha and Casper talking he convinces Ra that he was becoming his mindless minion. Casper was able to convince Ra that he wasn't becoming a vampire when he pointed out Ra still had his reflection in a mirror. Of course Thatch took out the mirror in the middle of the night and by morning Ra was now convince he was Thatch's mindless minion when he couldn't see his reflection. He was only able to finally be convince he wasn't a vampire after seeing his reflection in a pool of water inside the caverns. His best friends are Casper, Mantha and Jimmy.
Ra is voiced by Kendre Berry in the film. The TV series voice of Ra is unknown, due to the credits' confusion of voice talents.
A zombie. Mantha is able to remove parts of her body at will. Despite lacking any physical connection between her head and those parts of her body removed in this fashion, Mantha remains able to control said parts at all times (e.g., she is able to see using eyes removed from their sockets and detached from their optic nerves). This "ability" is sometimes a hindrance: unable to keep them attached to her body, Mantha once required a prosthetic replacement for her arms. She successfully proves that zombies can be scary too by defeating Thatch in a scaring contest, a feat accomplished by her luring of unsuspecting humans into Casper and his Uncles' haunted house. Mantha is very proud to be a zombie and sets out to prove that zombies are more than just "lumbering, mindless things that fall apart". In the episode You Oughta Be In Pictures she helped a group of zombies (not realizing they were actors filming for a movie) fight off some humans (also actors) that were attacking because she wanted zombies to defend for themselves and not let others push them around anymore. In the end of the episode she was the inspiration for 'Z, Queen of the Zombies' for a movie, which could help the reputations of other zombies. Her best friends are Casper, Ra and Jimmy. Casper possibly has feelings for her. In which Mantha is romantically involved with him too.
Wolfie is a shy but clever werewolf and one of Casper's closest friends, although the relationship seems on and off as he is not seen in Casper's company as often as Mantha or Ra, possibly because he's not an undead monster like Casper (Ghost), Mantha (Zombie), or Ra (Mummy). Wolfie is just like a puppy he likes to fetch, chase his tail and can't resist bones. He is usually picked on by Thatch and his gang, but every full moon, he goes berserk and has to eat in the corner of the cafeteria for the other students' safety; when this happens he grows 15 times his original size and he becomes very strong, very fast, and out of control and ferociously vicious. He once conducted an experiment in efforts to capture and harness moonlight when the moon was full, but it caused an energy surge that caused everyone in the school to act the opposite of how they normally would. Wolfie turned savage while Thatch turned nice, and Mickey and Monaco both turned smart. Casper, Thatch, Mickey and Monico had to find a way to reverse the affect without getting eaten by Wolfie. Wolfie once walked a mile in another's shoes when he turned into a human ("fleshie") and was banished from the school. Unfortunately, Alder & Dash plotted to turn him to stone, fearing he may reveal the secrets of Scare School to the humans. Luckily, Casper discovered that, by making Wolfie angry, he could become a Werewolf again. And Thatch, while insulting and scaring some other humans, got Wolfie angry when he had learned more about humans, and angrily stood up for them, bringing him back to his werewolf self, and he was allowed back in the school.
A green ghost who is the large-and-in-charge ruler of the underworld, usually seen terrorizing fleshies or at the scare school, he is feared by all, Alder & Dash especially. In the movie it is revealed that the reason he is so tough on Casper is because he used to be just like him when he was his age. Kibosh once posed as a monster that steals creatures' powers with the use of a magic crystal in order to get Scare School to work together, but things went out of control when his leprechaun servant Raznik stole the crystal and tried to take over. But thankfully, he was thwarted and Kibosh apologized for the whole mess and congratulated the students on their teamwork even without their powers and used the crystal to restore them to their rightful owners. He is voiced by Kevin Michael Richardson.
Fatso, Stinky and Stretch
- Main article: The Ghostly Trio
Their bio will be revealed in Casper's bio. These incarnations of the Ghostly Trio is unique as they actually treat Casper as their nephew, and not a slave they're disappointed of; though they still love scaring humans and fear Kibosh. They make several appearances during the series, sometimes to make money or to help their nephew.
Casper's human friend. Casper would occasionally leave the school to hang out with him. Jimmy is also friends with Ra and Mantha. He doesn't appear to have any human friends. His parents are at first unaware of their son's friendship with a ghost, but Jimmy's dad finds out in the special "Power Outage". Jimmy is one of the few humans who ever visited scare school. In the episode "A Real Little Monster", Casper took him to scare school, disguised as a creature named Jimbacca.
Jimmy is voiced by Brett Delbuono in the film.
Alder and Dash
Two-headed headmaster(s) who want world domination. Alder liked the quarter behind the ear trick and Dash liked music. Alder can be seen with a fez and Dash can be seen with a long straight forehead topped with an Academic Cap. Dash is the smarter, more conniving of the two, while Alder is slower on the uptake, but occasionally has good ideas. They are both rude and manipulative, and delight in causing the students misery. In the movie, they were fed up with being the headmasters of Scare School and concocted a plan, and a potion, to usurp Kibosh and take over the underworld. Their plans were stopped by the return of their "Ankle" (Aunt & Uncle), Belle and Murray. Their names are a pun on balderdash.
Thatch is the school bully at Scare School who is a vampire, mainly an antagonist in the film. He says he is, and seems to be popular, but a jerk instead, as he is conniving, selfish and mean. He is always looking for things to exploit and use to his advantage. His gang usually includes Slither, Dummy Girl, Mosshead and Harpy. In film, he deputise the Skeletwins (Monaco and Mickey).
Thatch displays vampiric traits, mostly his ability to shapeshift into a bat. But oddly, he seems to have no aversion to sunlight as he has been in Deedstown several times during the day. He apparently has acid for tears as he once cried for not having the respect of his gang, his tears burning holes through his cape.
Although he's a bully, once in a while he finds common grounds with Casper and his friends, and even occasionally helps them, but goes right back to being the way he was before, as if nothing happened.
Prof. Thurdigree Burns
Casper's Dragon Science teacher who thinks sweat is "scare juice". His name is a play on words for "Third-degree burns" which are caused by fire or intense heat, which he is able to breathe at will. He has a tendency to bark untrue facts about "Fleshies" (the creatures' word for humans), which Casper politely tries to correct, which only aggravates Burns. He once attacked a restaurant with a Medieval theme, mistaking the employees and customers for actual knights as an act of revenge for his ancestors. But thanks to Casper, who'd come to "help" Burns, no one was injured and Burn got a satisfied "victory". He even saved Casper from expulsion at Alder & Dash's hands when they thought Casper had taken off, but Burns said Casper had been assisting him.
The Scare School history teacher who can be only seen in a crystal ball with her head floating together with a small table, and she possesses the power of Levitation. She greatly resembles Madame Leota of Haunted Mansion fame. She's in love with Frankengymteacher.
The Frankenstein monster who is a gym teacher. His lightbulbs glow red by anger. He usually tries to teach the students to avoid angry villagers with torches, made as a reference to Mary Shelley's Frankenstein, but usually scares himself through a wall (literally). He's in love with Heady.
The Gargoyles are somewhat of a security force for Scare School, as well as disciplining the students. They also have a magic brew that turns whomever's dipped into it into a Gargoyle statue, which they usually use on Fleshies.
Mickey & Monico
Mickey & Monico are twins who are skeletons. They are Thatch's henchmen until in the end of the film. The make-up on the twins faces resembles Mexican Day of the Dead skulls. They're the show's example of vain girls who always talk about make-up, their hair, and their weight even though they are just bones, and etc. Mickey is blonde while Monico dyed her hair pink.
The Cafeteria Thing
A purple monster that resembles an octopus. The only thing seen on-screen are massive, magenta-purple tentacles. She serves the students food during lunch.
The Scare School Nurse is a Gorgon, evident by her snakes fo hair, but her gaze doesn't turn people to stone. But that does not mean she isn't scary because she often prescribes painful or dangerous treatments for her patients, which she seemingly has no idea of the fear she instills.
The Sea Monster
The Sea Monster lives in the moat around Scare School. He's a long, purple, reptillian serpent with a dragonish head, but despite his monstrous demeanor he's actually friendly but pretends to be vicious. He's also friends with Casper.
Mosshead is usually a background character, and a part of Thatch's gang. Casper once invited him to his manor for vacation but he proved to too much of an annoyance, but he and Casper made amends. He also finds out Casper's friends with Jimmy. He seems to be some sort of swamp creature, speaks with a southern accent, and is always praising Thatch.
A background character who is part of Thatch's gang. He appears to be Emo or Goth, and some kind of snake creature, hence his name. He has tentacles for arms.One of the few that have tentacles. He has a crush on Dummy girl.he is the best
A background character who is part of Thatch's gang. She's a living marionette/puppet/dummy. Her special "creature" power is her ability to be funny, although the other students said they wouldn't be able to tell if she lost it, meaning they probably don't think she's that funny. She has a crush on Slither.
A background character who is basically your typical hunchback ogre monster. He is friends with Casper and gets stuck with the job of turning on and off the lights and ringing the school bell, the latter he hates doing.
A background character who got detention for messing with the teacher's door. He is a fly that talks and tells funny things to people. His name is mentioned by Ra. In one episode, his father told flyboy and his friends that he used to be human, and then tried changing himself and his son into humans but stopped after realizing that his son liked being a fly.
Triclops is a three-eyed shy girl, but is usually a background character. She was once a victim of Thatch, who was suffering a toothache, after he stuffed her in a cupboard. Although she is a background character, her friends are Casper, Ra, Mantha, Dummy Girl and Pumpkin Head.
A student with a jack-o-lantern for a head, usually a background character. Like Mantha, his head sometimes falls off.He can also breathe fire,but to a lesser extent than Prof. Thirddegree Burns.
A female bird creature student and Ra's one-time girlfriend , usually a background character in which she is usually a part of Thatch's gang. She first appears in the film, where she was in the Valley of the Shadows. She is shown to not be able to speak like that of other students, but only able to cluck. She dated Ra in a dance, initially too forceful, but with Casper, Mantha, and Wolfie's help, she and Ra were crowned the dance's king & queen, after displaying excellent dancing and teamwork.
Bell and Murray "The Ancle"
Alder and Dash's aunt/uncle (ancle). Murray likes playing magic tricks and Bell loves singing. They look a lot like Alder and Dash except their clothes. Bell and Murray are voiced by Captain and Tennille who looks and sounds like them.
She works at a grocery store dressed up as a banana giving free samples, first seen in the movie, she kept saying "banana cheese." She's apparently not happy with her job. She got scared by Fatso, and later seen running from . Once in the show she says "would you like a poo with that!"
A leprechuan and the servant of Kibosh, Razzik, sick n' tired of being treated like a slave, stole a crystal from Kibosh to steal the powers of the creatures in Scare School, stealing Thatch's power to turn into a bat, Heady's Levitation, Frankenteacher's Franken Strength, Burns's Fire-breathing, Wolfie's Werewolf powers, Mantha's Zombie powers, and scores more. But what he wanted was Ghost powers so no Creature would be able to escape him (A Ghost's Intanability), and take over the Underworld. Thankfully, the students figured out Razzik's weakness as a leprechaun: He must obey the one who gets his Pot of Gold at the End of the Rainbow. Exploiting this, the students stopped the greedy leprechaun and everything was set right while Razzik was imprisoned. It is unknown if he will return for the announced second season.
A bully who picks on Jimmy. His appearance seems inconsistent; he is either a brown mullet-haired boy ("What Possessed You?") or a blond skater ("Shrinky Dust" and "A Real Little Monster"), however both boys appear to be seen together ("Bands On The Run", "What Possessed You?" and "Power Outage Part 3") so its likely they have the same name. The mullet-haired Norman first appeared in the movie eating in the store, and was scared away by the Ghostly Trio. The blond Norman has a sister named Bethica who would stop him from bullying or threatens to tell their parents. The mullet-haired Norman appears to be pretty much aware of Casper's relationship with Mantha as he threatened to mail her head to China, which made Casper show him how to get back home("What Possessed You?").
Comic Exclusive Characters
A new student that appeared in the second story of the first issue ("The New Kid"). He may appear human, but in reality he becomes monstrous when frightened or angered. Jackie is somwhat a parody of Dr. Jekyle and Mr. Hyde. It is currently unknown if he will appear in the announced second season.