Ms. Grunkle
- "So, at last we meet in my domain. Rather brave, aren't you? I must admit, I never thought you'd get this far. But no matter. It's just a shame you missed that fateful day when all of your classmates turned to monsters. Now it's your turn, but not until I have some fun with you first. Out, I say, out!"
The apparent ruler of Haunted Island, an evil and troublesome witch. She has turned your classmates into monsters and imprisoned them in the attic of her house.
- Big Bad: The cause of all the children turning into monsters; you find that she causes problems for other people on the island too, like the frog prince and even Flap.
- Flat Character: We never really know her motivation for turning the kids into monsters, how she managed to con her way into a substitute teacher job or even why she's the ruler of the island, she's just the villain who needs to be stopped.
- Hidden Depths: If the info gravestones scattered around the island are any indication, Ms. Grunkle apparently takes teaching quite seriously and even has a favorite subject: geology.
- Karma Houdini: After you set your classmates free, she flees her house and promises to meet you again.
- Random Event: She occasionally appears to you at random after you beat a mini-game, albeit unlike Repsac she only taunts you.
- Wicked Witch: And a stereotypical one, to boot, only missing a black cat.
Repsac
- "Select the correct answer if you wish to pass."
An evil ghost who serves as the keeper of the island and as Ms. Grunkle's right-hand-ghost.
- The Dragon: To Ms. Grunkle.
- The Dreaded: Both in the game and out of it; most players are more afraid of him than they are of Ms. Grunkle, and for good reason.
- Meaningful Name: His Sdrawkcab Name indicates he's the exact opposite of Casper: A very unfriendly ghost.
- Random Event: Every now and then, he randomly appears and asks you a riddle, which takes the form of an educational question. If you get too many of his questions wrong, you'll be sent to the Labyrinth. Oh, and he can catch you in there too.
- Sdrawkcab Name: His name is "Casper" spelled backwards.
Flap
- "Well hello... what a nice specimen you'll make, *laughs* Oh, I didn't recognize you! You're one of the kids, aren't you?"
A giant purple bat who talks like Peter Lorre and serves as your guide through all the minigames on the island. Apparently considers himself to be everyone's best friend, although it's never explained why he was looking for a "specimen" initially...
- Exposition Fairy: He explains all of the mini-games and your overall objectives, and can be summoned for tips at any time.
- Forced Transformation: The old Knowledge Adventure website gives him a more fleshed out backstory, claiming he was once a child turned into a bat by Ms. Grunkle. This is likely the reason he's so sympathetic to your case.
- Freudian Slip: In the re-release, when you first meet, he tells you happy "haunting" before quickly correcting himself and saying "hunting."
- Lorre Lookalike: As described above, Flap's voice sounds like Peter Lorre.
Madame Pomreeda
- "Oh, I'm so glad you've come. I've been expecting you. The children certainly need your help."
A Fortune Teller who assigns you your missions.
- Big Good: Judging by how Ms. Grunkle is able to immediately guess she's responsible for you having her wand, the fortune-teller apparently makes it a habit to stop the wicked witch when possible.
- Fortune Teller: And a stereotypical one, to boot, complete with an accent, caravan, and crystal ball.
- Mission Control: Pretty much her role in the game. You contact her with a Crystal Ball in place of a telephone.
- Nightmare Fetishist: She finds bugs to be cute, and Flap himself says her sense of humor is rotten.
- Punny Name: "Pomreeda," i.e. "palm-reader".
- Tarot Motifs: Your missions are printed on tarot cards.
Frog prince
A talking frog whom you must turn back into a prince by brewing a magic potion.- Bewitched Amphibians: He was a prince until Ms. Grunkle turned him into a frog.
- Gonk: His human form is...not the best-looking.
- Shout-Out: Obviously, he's a reference to The Frog Prince. Don't worry, no kissing is required in this version, just fractions and decimals.
- Status Quo Is God: No matter how many times you turn him back into a prince, he's back to being a frog the next time you play the activity.
Graveyard ghost
The friendly ghost whom you save by writing an inscription on his tombstone, i.e. playing Mad Libs.- No Celebrities Were Harmed: He seems to be a ghostly parody of W. C. Fields.
Semimoto
A cheerful hunchback whom you help to play the piano. He wants to ring the tower bells, but has to finish his music lesson first.- The Faceless: Only his hands are ever seen.
- Shout-Out: To Quasimodo from The Hunchback of Notre Dame, naturally.
General
- Forced Transformation: All turned into monsters.
- Helpless Good Side: The poems Madame Pomreeda recites imply that the monster forms are evil alter-egos of the children, and that magic is required to allow their good side to resurface.
- Shapeshifting Excludes Clothing: Their clothes weren't changed when they were turned into monsters.
Wolfgang
Musical prodigy turned into a werewolf; he's the first child you have to restore.
- Child Prodigy: A musical prodigy, and a sweet looking little kid.
- Meaningful Name: "Wolfgang," which refers not only to his being a wolf but is also a reference to Wolfgang Amadeus Mozart.
- Our Werewolves Are Different: He's a wolf constantly, and one that stands upright and snarls.
Violet
Artist girl turned into a Medusa.
- Child Prodigy: If the framed portraits she possesses are hers, she's got quite a talent for a fourth-grader.
- Meaningful Name: "Violet," in other words a color, given she's an artist.
- Medusa: The monster she's become.
Albert Brayne
Math genius turned into a brain creature.
- Brain Monster: A monster with a brain for a head.
- Good with Numbers: As indicated by his possessions.
- Meaningful Name: "Albert" is likely a reference to Albert Einstein, while "Brayne" is a pun on "Brain."
- Lampshaded by Madame Pomreeda: "Ah, Albert. As in Einstein."
- Punny Name: "Brayne" being a homophone for "brain."
- Smart People Wear Glasses: One of the indications he's smart to Madame Pomreeda is that he possesses a pair of glasses.
Tiffany
Beauty queen turned into a warthog.
- Beauty Contest: She's the queen.
- Beauty Equals Goodness: Her beauty on the outside is intended as a reflection of her inner beauty, according to Pomreeda's verse.
- Beauty to Beast: The theme in her case, turned into a warty creature when she was once beautiful.
Calvin
School Clown turned into a monstrous Clown.
- Class Clown: Literally, as most of his possessions are clown clothes.
- Evil Laugh: When clicked, he gives one.
- Monster Clown: The monster he was turned into.
Joe
Class jock turned into a gorilla.
- Big Man on Campus: His archetype, although he attends a tiny schoolhouse.
- Extreme Omnivore: When clicked, he eats a football.
- Jerk Jock: The personality of his gorilla self, but the actual kid is apparently an aversion.
- Killer Gorilla: The monster he was turned into.
Laura Fizz
Class Representative who has a Multiple Head Case with the extra head being a vampire head.
- Alpha Bitch: The vampire head is apparently this, being a cruel leader as opposed to a kind and responsible one.
- Irony: As a class president, Laura is a politician of sorts. With two heads, she becomes a "two-faced" politician.
- Just Eat Him: Her transformation back to being a normal girl is her normal head turning around and swallowing the vampire one.
- Multiple Head Case: Unlike the other students, none of her features changed; she just gained an extra head.
- Status Cell Phone: One of her missing items.
Stanley ZeBlucky
Class dunce turned into Frankenstein's Monster.
- The Ditz: He gets all F's and has a dunce cap as one of his possessions.
- Dunce Cap: One of his missing items.
- Frankenstein's Monster: The monster he was turned into.
- Scary Stitches: Part of his design as a monster.
Zev Cosmo
Science whiz kid turned into a science experiment.
- High-Pressure Emotion: She has smoke coming out of her ears.
- Jekyll & Hyde: The monster she was turned into is a horrible woman named "Miss Hyde," as well as the original child being a scientist herself, making her into this archetype.
- Smart People Wear Glasses: She's another brainy student and naturally wears glasses as a regular human.
Jane Plain
Girl turned into a monster toy.
- Creepy Doll: What she turns into.
- Eating Lunch Alone: At one point, Madame Pomreeda says, "She can't be doomed to eat alone forever! Draw a card to save Jane."
- Security Blanket: Seeing as Jane is characterized as being shy, her teddy bear is likely meant to be this for her.
- Shrinking Violet: The original child is noted to be shy by Madame Pomreeda.
James
Butler kid turned into a monstrous penguin.
- Toothy Bird: A penguin with sharp teeth.
Debbie
Mechanic girl turned into a tire-headed monster.
- Girlish Pigtails: She sports some despite her traditionally masculine interests.
- Wrench Wench: Her original personality as an aspiring car mechanic.
Penny Scilin
Medical prodigy turned into an anthropomorphic hypodermic needle.
- Dressed to Heal: Wears a lab coat and stethoscope. Also, one of her personal belongings is a doctor's head mirror.
- Punny Name: Her name is a pun on "penicillin."
- Smart People Wear Glasses: A brilliant student who wears glasses on both forms.