Robot Electro Jones
A young robot who goes to school to learn the ways of humans.
- Character as Himself: Before he was given a voice actor and the older episodes were redubbed with the new voice, Robot Jones was credited "As Himself".
- A Dog Named "Dog": He's a robot whose first name is Robot.
- Funny Robot: A major source of humor on the show is Robot's warped perception of human culture and trying too hard to fit in.
- Insufferable Genius: He will occasionally infuriate others by gloating about being smarter than them, especially his math teacher Mr. McMcMc.
- My Brain Is Big: His lightbulb brain is huge and round and he is often very intelligent.
- Ridiculously Human Robots: He often demonstrates human-like behavior and needs, one example being when his need for an oil change in "Family Vacation" is treated like him having a Potty Emergency.
- Synthetic Voice Actor: He was originally "voiced" by a text-to-speech program before the higher-ups decided to have an actual voice actor record his lines for the remaining episodes and to redub the older episodes.
- Wacky Parent, Serious Child: He is frequently portrayed as being more sensible and realistic than his parents.
Timothy "Socks" Morton
One of Robot's closest and few friends.
- Only Known by Their Nickname: He's always addressed as "Socks".
Charles "Cubey" Cubinacle
Another of Robot's friends. His nickname comes from being good at solving Wonder Cubes.
- Cool Shades: A pair of 80s style Shutter Shades.
- Only Known by Their Nickname: He is only addressed as "Cubey".
Mitchell "Mitch" Davis/Freemen
The third of Robot's friends.
- Blinding Bangs: His eyes are covered up by his hair.
- Sudden Name Change: His surname is given as "Davis" in the episode "Scantron Love", but "Hookie 101" has Principal Madman look at a list of student names that has him listed with the last name "Freemen".
- Papa Wolf: In "Hookie 101" when Principal Madman chased Robot Jones and his friends down, he not only tells the arcade owner to call the police, but punches him.
- Synthetic Voice Actor: He is "voiced" by a text-to-speech program.
- Verbal Tic: He tends to say whatever he has to say three times in a row (e.g., "Go to school, go to school, go to school").
- Amazingly Embarrassing Parents: Played for Laughs along with Dad Unit in "Parents," where they inadvertently blow up the school.
- Education Mama: She considers it important that her son study something important to human culture every day and will get frustrated when Robot doesn't want to.
- Everyone Has Standards: Although she has difficulty interacting with humans due to her outdated human protocol programming, she won't hesitate to report suspicious behavior, such as when Principal Madman tried to sneak behind her house in Hookie 101, thinking he was a peeping tom.
- My Beloved Smother: She cares a lot about Robot Jones, though can be overbearing, as seen in "PU to PE."
- Pink Means Feminine: She's colored pink.
The principal of Polyneux Middle School who has nothing but contempt for Robot Jones.
- Dean Bitterman: He's a very ruthless and grouchy school principal.
- Fat Bastard: He's quite hefty and definitely despicable for how he treats Robot Jones and the other students.
- Hypocrite: He is a technophobe, which explains his disdain for Robot Jones for being a robot, but apparently he likes Finkman (an android) in "Jealousy".
- Jerkass: He gives Robot Jones a hard time just for being a robot and even attempts to frame him for various misdeeds in "School Newspaper".
- Meaningful Name: True to his surname, he's quite maniacal and psychotic at times.
- Putting on the Reich: He happens to look like Adolf Hitler and is very tyrannical to his students.
Lenny and Denny Yogman
A pair of fraternal twins who always make things miserable for Robot Jones
- The Bad Guy Wins: In "Cube Wars", they scramble Robot's mind to cheat their way through the rubiks cube tournament. and get away with it.
- Bald of Evil: Lenny is bald underneath his hat.
- Early-Bird Cameo: They appear as background characters in the pilot prior to their proper introduction in "Electric Boogaloo".
- Evil Plan: They want to take Robot Jones' brain so they can use it to take over the school.
- Jerkass: When they aren't trying to steal Robot's brain, they tend to cause trouble for him just because.
- Lean and Mean: Lenny is tall, lanky and rotten to the core.
- Nice Hat: They both wear Devo energy domes.
- Theme Twin Naming: Their names rhyme.
Robot Jones' unrequited crush, whom he appears to be attracted to mainly because of her braces and her prosthetic leg.
- Braces of Orthodontic Overkill: Her braces happen to include unsightly headgear to keep them in place.
- Depending on the Writer: How she feels about Robot isn't consistent. Sometimes she treats Robot like crap and sometimes she is at least fine with associating with him.
Robot Jones' grandfather.
- Racist Grandma: He generally views humans in contempt. His grandson even worries about him killing human guests he invited over in "House Party".
- Synthetic Voice Actor: As with Dad Unit and Robot (in the initial airings of the older episodes), he is "voiced" by a text-to-speech program.
The math teacher at Polyneux Middle School.
- Berserk Button: He gets infuriated when Robot infers that he is smarter than him.
- Stealth Pun: Take another look at his name: MC Cubed!
The gym teacher of Polyneux Middle School.
- Ambiguously Gay: His voice is somewhat effeminate and he coaches a team called the Rainbows.
- Laser-Guided Karma: He spends most of the episode "P.U. to P.E." attempting to get Robot to take a shower against his will, completely ignoring Robot's concerns that getting wet will cause him to rust. In the end, Robot showers and doesn't rust, but instead Mr. Workout gets electrocuted.
Clancy Q. Sleepyjeans
The janitor of Polyneux Middle School.
- Mysterious Middle Initial: It's unknown what the Q stands for.
An Austrian android exchange student who once showed up to torment Robot and get off scot-free.
- Chick Magnet: All of the girls at Polyneux Middle School adore him and are unaware of what a jerk he truly is.
- Jerkass: He's a smug prick who enjoys pissing Robot off.
- Karma Houdini: He manages to weasel out on Robot retaliating against his bullying of him solely because his time in the United States had conveniently run out.