'''''Main Characters'''''

!!'''Joel Dawson'''

Resident mad scientist of the show, Joel spends most of his time inventing insane things and making Phil's life unmanageable.

* AntiGravityClothing: In his final art design, his hat floated above his head.
* BigOlEyebrows: His final art design used these. Before then he had no eyebrows except to emote.
%%* BrilliantButLazy
* CharlieBrownBaldness: His design for the first two seasons had only four long hairs coming out of his hat, even though his ''High Score'' design had thick blond hair. His altered form in "Project 2" and "2 Fast" and his later design from season 3 on revealed that his hair was supposed to be blond.
* ChickMagnet: In High Score (before Bonus Stage), Joel was presumably June's boyfriend (she's much less acknowledged in Bonus Stage), but even in Bonus Stage, Joel's the object of Elly's affection, he starts dating Jessica, and then it's later revealed he has an ex-wife.
* CloudCuckoolander: Many of his "inventions" were pretty out there, even for being a mad scientist.
--> '''Phil''': What does it do?
--> '''Joel''': YourMom.
--> '''Phil''': That's... actually pretty impressive.
--> '''Joel''': Yes. I call it the ''Up Yours''.
%%* TheDitz
%%* TheFool
* GeniusDitz: He's a damn good inventor/scientist when he wants to be, but he often lacks common sense, doing things like purchasing and wearing shoes of death.
* JerkAss: While the vast majority of the cast qualifies, Joel is one of the biggest offenders.
--> '''Joel''': I made Elly cry...''awesome!''
--> '''Blakken White''': Congratulations! ''{{{beat}}}'' You're an asshole!
* KilledOffForReal: [[spoiler:{{Subverted|Trope}} in "Morbid", which was the first of many temporary deaths.]]
* LongPants: Most of the time his feet were the same shade of blue as his pants.
* MadScientist: Often makes inventions for his own amusement.
--> '''Jessica''': Well, what can you do with it?
--> '''Joel''': Well, on some scale, collar crooks, find the terrorists, improve the economy... but mostly I just intend to mess with peoples' lives, which is far more fun.
* {{Pirate}}: He claims to be, and in two episodes, he acts like one.

!!'''Phil Argus'''

Joel's roommate and straight man.
* TheAlcoholic: More of an InformedAttribute, as his alcoholism is brought up a lot more than he's ever shown actually drinking. But it is brought up quite a bit.
* ButtMonkey: While other characters are killed mercifully or quickly, Phil is more often killed slowly and painfully, screaming the whole time.
* DoggedNiceGuy: If he's trying to be nice to someone, expect it to backfire.
* InformedDeformity: Phil is treated as horrifically ugly, especially by women, despite not looking appreciably different from any other character. As with many character traits in the show, this is increasingly forgotten later on.
* JerkAss: Moreso to Joel than anyone else.
--> '''Joel''': What, do you still hate me?
--> '''Phil''': Yes.
--> '''Joel''': Awesome.
* ShipperOnDeck: Made a FanFiction shipping himself and Elly.
* StraightMan: A relatively level-headed foil to Joel.


!!'''Elly Strife'''

Joel and Phil's neighbor, and the target of Phil's affection, but she only has eyes for Joel.
* EyeGlasses: Throughout the series. In "Fickle Nickel", she has normal eyes without glasses. Her sixth-season redesign includes brown pupils in the white within the lenses.
* OrangeBlueContrast: For the fourth and fifth seasons, she wore an orange undershirt under a blue shirt; afterwards, the outer shirt switched to white.
* StalkerWithACrush: Starts off as one to Joel but mellows out as the series goes on.
-->(From one of Phil's flashbacks) "I love Joel even though he doesn't love me."
* YouGottaHaveBlueHair: Her hair is a bright shade of green.

!!'''Rya Botkins'''

A DeadpanSnarker RobotGirl, built by Joel to be Phil's girlfriend.

* DeadpanSnarker: Even moreso than the rest of the cast.
--> '''Keen:''' And what were you doing during that time?
--> '''Phil:''' Lifting weights... looking handsome.
--> '''Rya:''' Objection, your honor. Phil is not handsome.
* DeceptivelyHumanRobots:
** In her first episode, the characters don't realize she's a robot until she speaks.
** Apparently, Craig didn't realize she was a robot, even ''after their (clearly robotic) son was born''.
* FieryRedhead: Mostly just snarky in the second through fourth seasons, but she gets aggressive towards Evil before being shut off in "Evil's New Groove", and she goes through a killing spree in "Joel vs. the Monobrow".
* JerkAss: Hates pretty much everyone, and it shows. Later in the series, she arguably delves into JerkassWoobie territory, what with her desire to [[spoiler: become human]] and all.
* KilledOffForReal: [[spoiler:In "Ryaconning", she dies due to being in real human form when she is stabbed by the Cloaked Figure.]]
* PinocchioSyndrome: Later on, she expresses [[spoiler: a desire to be a real human in the real world. Eventually fulfilled, but she dies soon after.]]
* RoaringRampageOfRevenge: Had one after she and Craig broke up.
* RoboticPsychopath: Hates most of the cast.
* {{Sexbot}}: Played with. While she was built to be Phil's girlfriend, and is capable of sex (and, for whatever reason, pregnancy), Craig learned the [[GroinAttack hard way]] that sex with Rya can be downright dangerous.
* SyntheticVoiceActor: Was voiced by a Macintosh text-to-speech synthesizer for her earlier appearances. Later went on to being a ComputerVoice.
* {{Tsundere}}: Type A, to Phil, as a result of Joel trying to hard to make her "hard to get".


!!'''Jessica Argus'''

Phil's de-aged mother.

* AbsurdlyYouthfulMother: Looks and acts 25 years old, due to Evil activating Joel's Sitcom Reactor.
* ChristmasCake: In a sense. Jessica is chronologically middle-aged, but is physically and mentally in her mid-20s; however, it's implied that Joel was attracted to her even before she was de-aged.
* CloudCuckooLander: By the time the team lands on Hydrox, she's more of one than Joel, mouthing off non-sequitur sentences and phrases.
* TheFundamentalist: Prior to her exposure to the Sitcom Reactor, Jessica was an extremely overzealous Catholic.
* GranolaGirl: She is a vegan, though ironically enough loves {{ultraviolent video game}}s.

!!'''Cassidy'''

A former classmate of Joel, Phil, and Elly. Was known as Hat Boy in grade school.

* EarlyBirdCameo: Appeared as "hat boy" in a flashback in episode 61, "Fist World", before her first appearance as a non-extra in episode 71, "Joel Goes to College".
* LoveMakesYouEvil: [[spoiler:According to WordOfGod, Cassidy was the cloaked figure from episode 79--her motivation behind killing Rya (and, had the series continued, attempting to kill Elly) was that she viewed the other girls as threats to her potential relationship with Phil.]]
* MurderTheHypotenuse [[spoiler:Her attempts to do this caused the events of "Ryaconning" and would have driven season eight.]]
* NiceHat: Which was apparently her defining feature as far back as ''grade school''.
* OnlyOneName: While all the other major characters have at least had their surnames alluded to in some way (such as Rya's being shown as Botkins in the credits to one episode, and June's being shown as Crane in High Score), Cassidy's is never mentioned, not even as a joke.
* SheIsAllGrownUp: She was known as "Hat boy" in grade school because no one bothered to ask her gender.
* StalkerWithACrush: [[spoiler:Attracted to Phil enough to try, and in one case, succeed in, killing others she views as a threat to their relationship.]]
* {{Yandere}}: [[spoiler:She initially seems sweet and level-headed, but her apparent StalkerWithACrush feelings towards Phil and the fact that she killed Rya as a result could definitely place her under the Yandere heading.]]
* YouGottaHaveBlueHair: Gradient black/blue, possibly intended to be viewed as black with blue streaks.

!!'''June Crane'''

A former (and possibly current) girlfriend of Joel's. May or may not be a robot.

* AmbiguouslyHuman[=/=]AmbiguousRobots: Never clearly revealed whether she is a robot in Bonus Stage. ''High Score'' June was less ambiguously a robot.
* BareYourMidriff: Her usual outfit is striped sleeves, a bandeau and either a skirt or pants.
* DetachedSleeves: Striped sleeves and a bandeau.
* TheScrappy: In universe, everyone seems to go out of their way to not acknowledge her.
* YouGottaHaveBlueHair: Magenta in earlier episodes, a more purplish shade later on.