Billy O'Toole
Voiced by: Ashley Brown
The Leader of the kids who face off against Earl P. Sidebottom's evil schemes every day.- Character Catchphrase: "It's what I do."
- Token White: In his group of friends.
Lydia Lopez
Voiced by: Terri Hawkes
A (probably) Hispanic girl and one of the main 4 kids.- Alliterative Name: Lydia Lopez.
- Ambiguously Brown: She's most likely Hispanic, but it's never addressed in universe.
- Braces of Orthodontic Overkill: Lydia has braces for the entirety of the show. In one episode she gets headgear.
- Girlish Pigtails: Wears her hair in two pigtails.
- Otaku Surrogate: Is a big fan of comics, much to Billy and Marcus' surprise.
- Tomboy and Girly Girl: The Tomboy to Ruby's Girly Girl, although she's far from a traditional tomboy.
Marcus Snarkis
Voiced by: Tracey Moore
The youngest and smartest of the main 4 kids. He is the younger brother of Ruby, having skipped a few grades.- Annoying Younger Sibling: Ruby thinks of Marcus as this.
- Black and Nerdy: Marcus is African American and fits the nerd stereotype.
- Child Prodigy: He skipped a couple of grades and is in the same class as his older sister Ruby.
- Sensitive Guy and Manly Man: The Sensitive Guy to Billy's Manly Man.
- Smart People Wear Glasses: Marcus has skipped two grades and wears glasses.
- Tagalong Kid: In the sense that he's he youngest.
Ruby Snarkis
Voiced by: Tracy Ryan
The last of the main 4 kids and the older sister of Marcus.- Cool Big Sis: Ruby has her moments being this to Marcus.
- Deadpan Snarker: Most of Ruby’s snark is directed towards Marcus.
- Drama Queen: Her goal in life is to become an actress.
- Girlish Pigtails: Has three pigtails for some reason.
- Jerk with a Heart of Gold: Shes sometimes hot-headed, but still cares for her friends.
- Tomboy and Girly Girl: The Girly Girl to Lydia's Tomboy.
Earl P. Sidebottom
Voiced by: Richard Binsley
The show's Big Bad, also known as The Phantom. A boy genius who turned evil after receiving a D in shop class and retreating to the school's basement in shame. Every day, he terrorizes Flying Rhino Junior High with his reality-warping computer in retaliation for this grievance, and it's up to the main 4 kids to stop him.- The B Grade: Why Earl became the Phantom, except it was a D grade.
- Cut Lex Luthor a Check: Back in the mid-1970s, he invented the first handheld video game, a handheld version of Pong called the Mongo Pongo. He could have been quite wealthy if he'd stuck to producing these and other video games. In the real world, a handheld electronic game of this sort wouldn't be invented until 1979, and his Mongo Pongo would have sold a lot of games by then.
- Disproportionate Retribution: Why is he evil? He got a D in shop class. And that's not all; almost all his acts are motivated by someone in the school doing or saying something he considers insulting.
- Evil Genius: Becomes this after he adopts his new identity as The Phantom.
- Evil Laugh: All the time.
- Hair-Trigger Temper: He is angry all the time at the slightest provocation. To be fair, with a guy like Raticus as his minion...
- Insufferable Genius: It's this quality that isolates him from everyone else, long before he became The Phantom.
- Large Ham: And how...
- Laughably Evil: He might be able to warp reality, but he is hard to take seriously.
- Reality Warper: He has a machine that can alter the space-time continuum within the confines of the school.
- Small Name, Big Ego: Earl has an inflated ego, but most students and teachers think he's nothing more than an urban myth.
- Theatre Phantom: Earl lives underneath the school and constantly wants people to call him 'The Phantom'.
- Yank the Dog's Chain: He finds his old Mongo Pongo after over 30 years which (somehow) catches a school wide computer virus (despite not being connected to the rest of the system) and shorts out his console. Although, knowing Earl, he likely repaired that within 15 minutes (and had unsold copies of the game), but still, he seemed like he would have cancelled this episode's evil plan had he gotten to enjoy it for more than 30 seconds.
Raticus
Voiced by: Ron Rubin
A giant rat who was granted intelligence by Earl P. Sidebottom to act as his henchman.- Affably Evil: He's best friends with his master, Earl, but is actually quite nice and friendly.
- Minion with an F in Evil: He tries to be evil, but he's comically bad at it.
- Talking Animal: A giant rodent capable of cognitive speech.
- You Dirty Rat!: Downplayed; he is on the evil side, but he is rather nice compared to his master.
Principal Mulligan
Voiced by: Len Carlson
The principal of Flying Rhino Junior High, who is a talking rhino (and no one's asking why). Even more inexplicable than his appearance is his inability to notice any of the weirdness caused by Earl P. Sidebottom that happens around his school every day.- Inexplicably Awesome: There are absolutely no details about why the principal is a rhino.
- Suspiciously Specific Denial: "There is no phantom in the basement."
- Only Sane Man: Despite being a talking rhino, he's the most "normal" of the main characters.
- Weirdness Censor: Despite being a talking rhino principal (which is weird by itself) he's unaware of anything bizarre going on in his school.
Mrs. Snodgrass
Voiced by: Lindsay Leese
The science teacher of the main 4 kids. She never really reacts negatively to all the crazy stuff that happens around the school, instead seeing them as teaching opportunities for her students.- Cool Teacher: Her students seem to think so.
- Weirdness Censor: Seems largely unaware of the reality alterations that happen during class (or tries to avoid thinking about it).
Buford
Voiced by: Paul Haddad
The school custodian, who is both a talking pig and a former secret agent. He's much more aware of the wacky things that happen at Flying Rhino Junior High than the other staff are, so he sometimes helps the kids deal with them.- Almighty Janitor: Literally.
- Retired Badass: Was a former CIA agent.
