Mrs. Jeepers
- Everything's Sparkly with Jewelry: She wears a green broach on a choker around her neck, and it's largely implied to be what allows her to walk around in daylight. Notably, when Mrs. Zork touches the jewel and it becomes dull, Mrs. Jeepers begins to panic.
- Fiery Redhead: Downright scary when she gets angry.
- Friendly Neighborhood Vampire: If she is a vampire, she's a nice one. While she can be a bit scary at times and is implied to hypnotize people, she is never seen harming anyone and genuinely cares for her students.
- Hidden Depths: Despite possibly being a vampire, she is shown to care about her students from time to time.
- Magical Accessory: Her signature green broach is implied to grant her the ability to safely walk around in daylight without being injured. Any time the jewel becomes dull, Mrs. Jeepers will either panic or start to lose energy.
- Maybe Magic, Maybe Mundane: She is the main argument about this trope within all the books, as the kids can never agree if she's simply a stern teacher or a very restrained but menacing vampire.
- Noodle Incident: It's never clarified just what she did to Eddie at the end of book one. He tries to pass it off as just a scolding in subsequent books, but it's clear he's hiding something, and he's shaken whenever it's brought up.
- Not So Invincible After All: Just because she's implied to be a vampire doesn't mean it grants her immunity from the possible abilities of all the other supposed monsters who arrive in Bailey City. She possibly falls victim to both Mrs. Zork's color draining and Mrs. Rosenbloom's love potions.
- Stern Teacher: She won't tolerate bullying or horseplay from any of her students, but she doesn't play favorites either and can get offended on behalf of her students if some other adult insults them. One of the best examples occurs in Frankenstein Doesn't Plant Petunias when she gets injured during a hailstorm that starts to destroy Frank's greenhouse. Dr. Victor comes in and initially assumes the kids are destroying stuff until Mrs. Jeepers calmly reveals the kids were trying to help her and Frank, and that her students are not monsters.
- Took a Level in Cheerfulness: During Genies Don't Ride Bicycles, she suddenly becomes very chipper and starts doing stuff like handing out candy to the kids during class as Christmas approaches. While the kids originally love this change in demeanor from her usual iciness, Mrs. Jeepers quickly goes overboard and starts to get annoying. She thankfully reverts to normal by the end of the book.
Mr. Jenkins
- Carpet of Virility: He is a very hairy man, and he seems to get hairier as the full moon approaches.
- Depending on the Artist: How wolfish he appears varies from book to book. Conversely, sometimes he'll appear virile but ruggedly handsome, but other times he'll appear legitimately ugly. He's positively gonkish in Monsters Don't Scuba Dive.
- Jerk with a Heart of Gold: Has a deep love of nature, and noticeably softens up when the kids come to see it the way he does.
Mrs. Zork
- Aliens Speaking English: Her perfect, albeit broken, English is one reason the kids suspect her of being an alien.
- Deliberately Monochrome: When she first arrives, her outfit is colored in white, silver, and black. As time passes she begins to adopt more colorful additions to her wardrobe, which is believed to be a sign of her stealing color.
- Rubber-Forehead Aliens: Looks perfectly human except for the fact that her entire body and all of her clothes are completely grey.
- Slasher Smile: She has a very unnerving smile in a number of the illustrations, not helped at all by her braces.
Eugene
- Bald Mystic: He's a bald man who may or may not be a genie, with all being a genie entails.
- Magical Negro: The cover illustrations depict him as a dark-skinned man.
- Meaningful Name: The possible genie is named Eugene.
- Nice Guy: If he is indeed a genie, he goes out of his way to grant wishes, and takes no advantage of them at all.
Nessie
- Loch Ness Monster: Supposedly who she is.
Mrs. Rosenbloom
- Anti-Villain: She's one of the most benign "monsters" in the series, with the worst thing she does is getting people to fall in love with one another. Possibly.
- Big Beautiful Woman: Is noticeably a very large woman, but also very cute and well-groomed.
- Big Fun: Is incredibly cheerful and especially fond of hugs.
- Foul Cafeteria Food: Averted. Her food is not only delicious but also artfully presented as well.
- Gender Flip: She's believed to be Cupid of Roman mythology even though Cupid was thought to be male.
- Lady in Red: Red's her predominant color.
- Love Freak: She's nuts about love and especially loves Valentine's Day, to the point all the food she prepares is heart-shaped.
- Love Potion: Gives out heart-shaped sugar cookies which appear to have this effect.
- No Celebrities Were Harmed: For some reason, she has an uncanny resemblance to Bette Midler.
- Shipper on Deck: Since she's thought to be Cupid, she naturally seems to tend to pair people up romantically via her cookies.
- Supreme Chef: She has to be to get people to eat her sugar cookies.
The Bailey School Kids as a whole
Howie, Eddie, Liza and Melody
- Amateur Sleuth: Definitely. Regardless of whether or not the mystery is solved.
- Ax-Crazy: If the people they encounter aren’t monsters, then they have endangered everyone multiple times, physically hurt and possibly traumatized innocent people, and probably have suffered Sanity Slippage at some point in their young lives.
- Badass Adorable: If the adults are monsters, then these kids have run a leprechaun, a ghoul, Frankenstein, a wizard, a gremlin, and a sea serpent out of town.
- Cassandra Truth: If the people they suspect of being monsters are monsters, then no one ever seems to believe the kids even though they are right and therefore this trope applies.
- Cloudcuckoolander: If the adults aren’t monsters.
- The Greatest Story Never Told: If the adults are monsters, then all of the kids' adventures fall into this territory, as they have been Hunter of Monsters who have managed to go completely under the radar and receive no reward or recognition for their efforts.
- Karma Houdini: If the adults are not monsters, then these kids have caused a lot of trouble and aren’t always punished for it.
- Kid Hero: If the adults are monsters, then they have saved their town many times.
- Lack of Empathy: If the adults are not monsters, then these kids are harassing, stalking, and assaulting other people and never once express any regret or sympathy.
- Paranormal Investigation
- Sanity Slippage: Assuming that the adults aren’t monsters, then thinking that every adult is a monster in disguise who is out to get you, definitely would qualify them like this.
- Snooping Little Kid: If the adults aren't monsters.
- Occult Detective: Possibly. If the adults are monsters.
- Weirdness Magnet: Regardless of whether or not the adults are monsters, these kids do attract some weird people.
Liza
- The Heart: Easily the kindest person on the team.
- Ms. Imagination: Very imaginative and always suggesting that the adults in her life are monsters.
Melody
- Adventure Rebuff: Usually refuses to believe that someone is a monster.
Howie
- All Up to You: In Cupid Doesn’t Flip Hamburgers, Howie is the only one not to fall under the love spell.
- Jumped at the Call: Usually suggests that someone is a monster.
Eddie
- Blood Knight: In a kid-friendly way, Eddie is the most confrontational of the kids and is always at the center of the action. Whether it’s fighting a monster, a chase scene, breaking into a house, or spying on someone, Eddie is always eager to be at the center of the adventure.
- Raised by Grandparents: His grandma.
Carey
- Hidden Depths: There are a few moments when the main characters will let her in on the fact, that they think that a particular grown-up is a monster and Carey always responds with some measure of caution and fear, suggesting that she believes that the adults are monsters but doesn't try to expose them because she is too scared.
- Lonely Rich Kid: Despite being annoying and self-centered, some of the books show that she wants to be involved with the main characters despite how much trouble she gives them suggesting loneliness.
Ben
- Ascended Extra: Got his spinoff.
- Spin-Off: Is the star of one called Bailey City Monsters.
