Clawdeen is the daughter of the Werewolf (also known as the Wolf Man). She is 15 years old, and is covered with fur, with two piercings in each of her wolf ears. She has a purple pet cat namedCrescent.
She is confident, outgoing, friendly and fashionable. Her favorite colour is gold. She has a large family, including Clawd Wolf and Howleen Wolf
A girl who goes on a date with Holt Hyde.  Her father (the Phantom of the Opera) teaches a keyboard class at Monster High.
She is mentioned in Holt Hyde's Diary and in the 'School's Out' diaries. Her first webisode appearance was in "Hiss-teria", and she now has a profile on the Monster High website. She is shown to be a bit of a diva, but that's just her independent spirit. Her father moved to New Orleans when she was young, where she picked up the local "twang" and a love for country music.
Spectra is the daughter of the Ghosts. She writes an anonymous gossip blog and an advice column for the Monster High student newspaper, and as such is a bit of a rumor-monger. As a ghost herself, she can float and pass through walls.
Abbey Bominable is the daughter of the Yeti (better known as the Abominable Snowman). She is an exchange student from "up north" and her native language is Yetish. She sometimes has trouble understanding English slang.
Deuce is the son of the gorgon, Medusa. He likes to skateboard and is interested in cooking. He wears sunglasses to prevent his turning other people to stone temporarily. One of his friends is a human, Jackson Jekyll, whose alter ego is DJ Holt Hyde.
Holt Hyde is the son of Mr. and Mrs. Hyde. He is a DJ and has a pet chameleon, Crossfade. He is in the book just with the name "DJ Hyde". DJ has a major crush on Frankie Stein and calls her "Firecracker" because she sparks him.
Jackson Jekyll is the son of Dr. and Mrs. Jekyll. He is a new kid at school, and believes he is a "normie" (no apparent monster influence), because he is unaware of his dual nature. In the books he has a crush on a girl named Melody Carver; he later finds out who he truly is.
He was first introduced in the Gloom Beach doll set and appeared as a student on the Monster High site in May, and his bio was added to the site in July. His first webisode appearance was in "Fear Pressure". His alter ego is Holt Hyde.
Gillington "Gil" Webber is the son of the River Monster. He wears a helmet containing water on his head when he is on dry land.
Gil was first seen in the webisode Blue Lagoona as the object of Lagoona Blue's crush. He is also friends with Slow-Moe and even acts as his wing-man in dealing with Ghoulia. He is shown to be a pretty decent guy.
He is also a zombie, and he wears a letterman jacket. He is one member of the school Basketball and Chess teams. Moe has shown to be fairly stoic and good natured. His first appearance was in the webisode Cyrano de Ghoulia. He hates Heath playing guitar, and destroys them once he starts.
She and her friends, the cat-girl twins, quit the fearleading squad in the webisode "Scream Building", leaving Cleo in the lurch. They later continue to sabotage and gossip about the ghoulfriends, though their plans usually backfire.
The twins are on the fearleading squad with Cleo and Toralei, but they quit when the entire team walks out in the webisode "Scream Building".
In season two of the webisodes they pal around with Toralei, causing mayhem, but don't speak themselves. In the 'School's Out' diaries, their names are revealed to be Purrsephone and Meowlody, but it's only since the characters got their own profile that it is known which twin carried which name.
The Monster High Facebook account is hosted by a mysterious student of Monster High, strongly suggested to be a girl. Very little is known about her, but she is good friends with most of the other students. It is also known that the Facebook student's parents for the longest time didn't allow her to have a pet. When on October 6, 2010, she finally was allowed to have one, she let the Facebook visitors decide and ended up with a pink male mini-dragon.
Dougey is a werewolf who previously went to Crescent Moon High, but now goes to Monster High. He's the werewolves' tough guy, acting as a secondary leader and enforcer to other dominant wolves that use their brains more than their brawn, such as Romulus and Howleen Wolf.
Gory is a vampire leader figure and was originally student at Belfry Prep, but transfered with Belfry Prep's student body to Monster High. She was introduced in "Fright On!". She is dating Bram Devein.
The Headless Headmistress is head of Monster High, and in charge of discipline. She takes after her name, and is able to remove her head from her body.
She rides a horse named Nightmare and carries a riding crop. Her character is inspired by the Headless Horseman from the classic story "The Legend of Sleepy Hollow". Teacher of Trigular Calcometry 101. Abbey Bominble and Shiver stay with her when Abbey starts attending Monster High.
The Monster High Science teacher seems to be a classic British torturer/executioner, with his accent, butcher's apron, leather mask and cabinet of weapons. He tries to make the students dissect three-eyed frogs, though Lagoona intervenes and frees them. He also serves lunch (first season only).
He has a mother (who looks like him, but with a old lady bun), who broke her back in "Freakout Friday", and a lab assistant in "Hatch Me If You Can".
Skinner College - B.S., Chemistry
Lancet and Czechit School of Science - M.S., Taxidermy
Mr. Where wears bandages, gloves, and a hat (Shown to use both a beret and a fedora) to make himself visible, and he tops off the ensemble with glasses and a scarf. And he can pop up anywhere. He also has the ability to extend his invisibility power to cloak his clothing as well.
Unlike the original character, Dr. Griffin from the H.G. Wells novel, he is quite sane and benevolent. He is shown to be very polite and an intellectual. His limited scenes of student interaction imply he is held in high esteem by the students, and he likes them as well.
Lou Zarr serves as a substitute teacher when one of the regular staff are unavailable, as seen in the webisode Substitute Creature, in the television special New Ghoul @ School. He appears to be the only regular human in the show. He is a stiff, humorless, uncompromising hardnose about education. His lessons are shown to be so boring they tend to put students, and even himself, to sleep.
Needless to say, his name is an obvious play on the word "Loser", and he's the first normie in Monster High.
One of the first teachers of Monster High, who got herself somehow stuck in a Greek statue without anyone knowing. She remained locked up for 2000 years, until Frankie Stein and Cleo de Nile accidentally freed her by breking the statue in "Totally Busted". It is unknown if she resumed her job as a teacher.
A teacher of whom only the voice is known, he was heard in the webisode "Parent-Creature Conference". Lagoona Blue is his best student, so much so that he personally wished to tell her parents. Since Lagoona's favorite subject at school is oceanography and no other teacher is confirmed to handle those lessons, it is possible he is the oceanography teacher.
Dead Fast is Ghoulia Yelps's favorite comic book hero and the protagonist of his own comic book series. He is a zombie who gained the power of superspeed after being bitten by a radioactive hummingbird.
He appeared as part of a Ghoulia-centered plotline for Comic-Con 2011.
Dr. Igorable is a human former employer and current enemy of the comic book hero Dead Fast. Igorable hates naughty and icky stuff, which he considers zombies to be, and wishes to rid the world of them. He doesn't like it when Dead Fast misuses his name by calling him "Dr. Deplorable".
Melody is percieved as being a normie. She once had a large nose, which her plastic surgeon father fixed for her, both for cosmetic reasons and to help her breathe better. The family also moved to Salem, Oregon to help with her asthma, and Melody has to start at a new school, Merston High. According to Cleo's servant Manu, she is the daughter of the Siren Marina, who it is later discovered, gave her up for adoption.
Candace is Melody's confident older sister. Though her constant optimism irritates Melody, her advice is, more often than not, extremely useful.
A huge flirt herself, Candace rarely keeps a relationship and looks at dating as more of a game than anything. She is one Billy Phaidin's best friends and gave him the idea of visibility. They started the NUDI (Normies Uncool withDiscriminating Idiots) group to promote RADs.
Billy is the invisible RAD introduced in the first book. He took a shine to Frankie and became one of her best friends, agreeing with her about RAD-Normie equality. It wasn't long before he develiped a crush on Frankie and it wasn't long before they decided to just be friends.
Billy is sarcastic, laid-back and loves to pull pranks. He strongly supports equality, and was a founding member of NUDI.
Bekka is the main antagonist on the Monster High book series. Though she seems innocent and friendly at first, but she backstabbed Melody when she found out that Jackson was a RAD. She is very discriminating against RADs, shooting out propaganda whenever she can. This hate mostly stems from the fact that Brett, her ex-boyfriend, chose Frankie Stein over her. By the third book, Melody used her newfound RAD powers to force out all her friend's true feelings. Bekka is left humiliated and friendless, increasing her hatred greatly. Between the second and thrid books she leader of the group HUNT (Humans Unite No Tolerance).
Brett started out as Bekka's boyfriend, but soon ended up with Frankie Stein, passing out into a coma when he saw her head fall off. He is a huge RAD supporter, and came up with the idea of a video where the monsters all poured out their feelings, but their faces would be blurred. The video was sabotauged and though he was originally accused, he cleared his name and got back together with Frankie.
Haylee is introduced as Bekka's best friend , though seems to be more of a servant to the girl. She was tricked Haylee into signing a contract promissing her friendship and loyalty to Bekka forever. This has completely backfires. She is mainly seen following Bekka typing her life into her phone for a phone novel titled : "Bek, and Better than ever!" In book three, Melody convinces Haylee to de-friend Bekka.