- Voiced by: Thomas Middleditch
An ordinary teenager-turned-hero who was forced to inherit the job after the disappearance of his part-time hero parents. Penn is energetic and sometimes overenthusiastic but is completely dedicated to his new career.
- Affectionate Nickname: Sashi occasionally calls him "PZ".
- All-Loving Hero: While he's capable of being angry or petty he generally seems to want the best for everyone, even the villains.
- Ascended Fanboy: In "I'm Super!", Penn reveals that he had wanted to be a superhero since he was six years old. Now, he's a part-time hero.
- Badass Normal: Depending on the dimension he zaps to, he doesn't always get any special skills or powers, but he is still capable of saving the world he is in.
- Character Tics:
- Gestures a lot when he's upset or trying to explain something.
- Tends to laugh nervously when confronted with something strange and/or horrifying.
- Penn commonly rolls his eyes with things that irk him, but in rare cases it's also because he finds that thing amusing as well.
- Chest Insignia: The symbol on his shirt is the linguistic form of zero.
- Crazy Jealous Guy: Spends most of "Where Dragons Dare" being upset at Boone and Sashi for liking Blaze.
- Dance Battler: Relies on agility and acrobatics during battles. It's connected to the fact that he's a really good dancer back on earth.
- Drives Like Crazy: His half of the "Chuckle City" chase scene is extremely chaotic and involves stunts like tilting the car onto its right wheels to cross a rope bridge — all while grinning cheerfully.
- Fiery Redhead: He quickly loses his cool whenever he gets impatient. Thankfully he is starting to improve after the events of "Rip-Penn".
- Gender Bender: Whenever visiting Fairy Tail world, he gets turn into a princess and swaps genders.
- Heroic Build: In the Superhero World, Penn is as muscular as a comic book hero ought to be, enjoying every second of it to the point of flexing really hard just to make them grow even bigger to the point that they dwarf his head. Also indicative of his Flying Brick abilities in that world.
- Hidden Depths:
- He's surprisingly manipulative for an All-Loving Hero, often exploiting opponents' emotional weaknesses to defeat them.
- Penn has dance skills and an eclectic taste in music.
- Iconic Outfit: His linguistic zero marked, long sleeve, collared t-shirt and chain mail undershirt, given to him by his parents. Amusingly the chain mail is a cheap, plastic replica from a Halloween costume that accidentally got packed in with the t-shirt.
- Improbable Weapon User: He's good at defending himself with whatever's lying around, be it a clipboard, a flare gun or, at one point, bacon grease.
- Improv Fu: Resorts to this when there aren't any weapons nearby.
- Kid Hero: When his parents got stuck in another dimension, he inherited their job despite only being a teenager.
- The Kirk: Acts as a buffer between Boone and Sashi's opposing personalities, as they get sidetracked by arguments if he isn't around to mediate. Appropriately enough, the episode where this is most prominent is one in which his form is a Shout-Out to the original Kirk.
- The Knights Who Say "Squee!": Depends on the world. Geeks out when they finally reach a superhero world but sort of lost interest in the cowboy world (along with Boone) until he discovered it had dinosaurs.
- Last Minute Hookup: With Sashi in the series finale.
- The Leader: He's the authorized leader of the team, though he doesn't have much confidence in his leadership abilities and only gives actual orders if the others are being particularly uncooperative.
- Meaningful Name: Penn's folks elaborate on why their surname is Zero. Namely, that they have zero failures as heroes.
- "Metaphor" Is My Middle Name: Zig-zagged in "Wings of Destiny."Penn: I'd say that "cooking" is my middle name, but it's actually "Albert".
- My Hero Zero: Penn's last name is Zero, and he's the hero of this cartoon.
- Nephewism: Lives with his aunt and uncle while his parents are away, or in this case, trapped in another dimension, namely the Most Dangerous World Imaginable.
- Nice Guy: Penn is brave, enthusiastic, and determined.
- Official Couple: Becomes one with Sashi.
- Ordinary High-School Student: He is attending high school while his dimension-hopping job is part-time.
- Part-Time Hero: It's in the title.
- Quirky Curls: His trademark hairstyle, which earned him the nickname "Cotton Candy".
- Red Is Heroic: Red, curly hair? Check. Part-time hero? Check.
- Refusal of the Call: Initially when he found out about his parents being part time heroes and him taking their place. But somewhat justified as all this information was practically thrust upon him in rapid succession before he could really process any of it. Being disintegrated in a training simulation certainly didn't help, nor did having no clue how to lead a team (especially with someone with Sashi's attitude at the time). He gets better over time and now fully embraces the job.
- Secret Legacy: Unbeknownst to him, Penn's parents were legendary part-time heroes. He only found out about this when he inherited the job after their disappearance.
- She Is the King: Whenever Penn is zapped into Oceanaquariopolis, he becomes the Prince. By the end of "Fish and Chips", his inability to tell which citizens are male and which ones are female reaches the point he's no longer sure about his character's own gender. Justified because the Prince wouldn't be the only female character Penn becomes in the series.
- Stepford Smiler: In regard to his family situation. He misses his parents more than he lets on, but assures everyone that he's doing fine so that they won't worry about him.
- Strong Family Resemblance: He looks just like a combination of his parents — he has his mother's curly, red hair and circular face; he has his father's eye color, eye shape, eyebrow shape, smile, and teeth structure.
- Sympathy for the Devil: Battling Rippen and Larry every day has given him a bit of a soft spot for them and he often tries to aid them in ways that won't affect the Balance Between Good and Evil.
- Unmoving Plaid: His hair does this with a red and yellow pattern.
- Voiced by: Tania Gunadi
Penn's friend and a part-time sidekick, though she tends to behave more like The Big Guy during missions thanks to her fighting abilities. Sashi is serious and a little too fond of violence but has an obvious soft spot for her companions.
- Action Girl: She has great combat skills and doesn't have any problems with using violence to solve problems.
- Affectionate Nickname: Penn and Boone sometimes call her "Sosh".
- Asian and Nerdy
- Badass Normal: During missions she often uses normal fighting techniques instead of the special abilities of the person she's acting as.
- Blood Knight: Shows some shades of this (enough to make Penn surprised that her parents let her babysit her baby brother). In " Zap One" dialogue suggests the main reason she chooses to be a sidekick and not a hero is she prefers more chances to fight.
- The Bully: In "Zap One", this was basically how she acted towards everyone, including and especially Penn and Boone, but she warms up to them later. As other episodes show, she still hasn't grown out of it towards anyone she doesn't respect.
- Character Tics: Briefly glances away from and then back to whoever she's interacting with when she's annoyed, embarrassed, or happy about receiving a compliment.
- Clingy Jealous Girl: While not quite as obvious as Penn is about her crush on Blaze, Sashi still has the tendency to be rather irritated when Penn gets too flirty with girls from other dimensions.
- The Comically Serious: Faces every situation, no matter how silly, with the same over-the-top gung-ho seriousness.
- Conspicuous Gloves: It's rare to see her without her violet gloves.
- Cosmic Plaything: The MUT will often assign her with the least desirable role out of the three.
- Crazy-Prepared: in case she had to fight a doppelganger of herself, she had a secret weakness installed in her shin.
- Cute Bruiser: Despite her size and appearance she's a skilled martial artist and is fond of melee combat.
- Death Glare: Gives Penn one of these when he tricks her into losing a dodgeball game in "Cereal Criminals". It's accompanied by fire and Ominous Latin Chanting.
- Defrosting the Ice Queen: She's warmed up to Penn and Boone by the time of North Pole Down.
- Expository Hairstyle Change: In the final scenes of the finale, she wears her hair in a loose, shoulder-length style, no doubt as a sign that she's moved on from her part-time sidekick work.
- Fashionable Asymmetry: Her tights have stripes on one leg but not the other, she's wearing one kneepad instead of two, and her eyeliner is intentionally mismatched. Her new hairstyle also invokes this, being smoother and longer on the left side than the right.
- Gender Bender: Whenever she visits the Fairy Tale dimensions, she gets turned into a male knight, much to her chagrin when Penn ends up both female and a princess.
- Goggles Do Something Unusual: Her glasses, which the gang refer to as "the Specs", can project holographic images that inform them about their missions. They can also receive calls and record audio/video.
- Hidden Depths: Despite her cynical, no-nonsense attitude, "The Princess Most Fair" reveals that she sometimes feels lonely and wants Penn and Boone to be more affectionate towards her.
- Hypercompetent Sidekick: A downplayed example. Sashi is extremely overqualified at her job but she does have flaws and vices, some of which are worse than Penn's, and Penn is usually perfectly capable of keeping up with her during missions.
- Jerk with a Heart of Gold: Sashi is cynical, serious, and can be mean sometimes. At the same time, Sashi is understanding and compassionate, giving Penn considerate advice and sometimes warming up to others whom she isn't originally mindful of.
- Kick Chick: Often kicks villains (and her two friends).
- Last Minute Hookup: With Penn in the series finale.
- Living a Double Life: Her parents are ordinary citizens, so Phyllis advised her not to tell them about her hero gig. They think Sashi works at Fishstick on a Stick.
- Mixed Ancestry: She (along with her brother) is half Japanese from her father and half Tongan from her mother.
- Official Couple: Becomes one with Penn.
- Ordinary High-School Student
- Part-Time Hero: She acts as Penn's part-time sidekick.
- Phrase Catcher: "Check the specs."
- Stalker with a Crush:
- "Totally Into Your Body" reveals that she sometimes follows an older student named Teddy around school. Boone is understandably creeped out by this discovery.
- "Where Dragons Dare" has her behaving the same way towards Blaze.
- Sugar-and-Ice Personality
- Tsundere: In "Totally Into Your Body" the specs play a clip of Sashi walking behind a student named Teddy while muttering about "heart"-ing him. When Teddy notices her and asks if she's following him, she hits him with her backpack and yells, "I do NOT love you!" before running off.Boone: That is not how you show Teddy you "heart" him.
- Tsurime Eyes
- Weapon of Choice: Given her Blood Knight tendencies it's no surprise that she favors bludgeoning weapons like clubs and batons.
- Wild Tongan
- You Gotta Have Blue Hair: Sashi has dark brown hair with violet and yellow highlights at the tips.
- Voiced by: Adam DeVine
Penn's friend and a part-time wise man. Boone is odd and a bit of an airhead but shows signs of being a surprisingly logical thinker, often pointing out errors and solutions that everyone else overlooked.
- Big Fun: The largest of his friends in size, Boone is easygoing, imaginative, and loves to have fun.
- Bunny-Ears Lawyer: Brought up in "The Fast and the Floor Rugs", where Sashi advises Penn to trust that Boone's unconventional solutions will work even when they seem like they won't. This is also the central theme of "Boone's Apprentice".
- Character Tics: Presses or taps his fingertips together when he's nervous.
- Cloudcuckoolander: From babies having nickels to mutated puppy monsters destroying the city, Boone definitely has a lot of unusual thoughts and ideas.
- Distressed Dude: An unfortunate side-effect of being a Non-Action Guy is that he's frequently captured by the villains.
- Does Not Like Shoes: He always wears flip-flops, no matter what role he plays. The exception in "3 Big Problems", where he's a giant monster.
- Genre Savvy: He's a bit of a film buff, which comes in handy when the gang find themselves in dimensions that abide by movie-logic.
- Gentle Giant: Downplayed. He's big enough to hold two teens off the ground with ease, but he's too disinterested in fighting to utilize this for anything more serious than dodgeball.
- Goofy Print Underwear: Boone's underwear has flip flop prints.
- Hidden Depths: Despite his carefree behavior he's very self-conscious and has severe anxiety issues. He's especially sensitive about people perceiving him as obstructive or useless, because he thinks it's partly true.
- Iconic Item: Flip flops are his thing and, if a zapped form has feet, he'll be wearing them.
- Jerk with a Heart of Gold: He can be rude, inconsiderate, and stubborn, but he usually means well and comes through for others when they need him.
- The Load: Can be this at times, with Penn calling him out on it during the events of "The Fast and the Floor Rugs".
- Mellow Fellow: The most easygoing of his friends.
- The Mentor: He's the team's wise man, which means his job is to advise and guide his fellow heroes, though he usually shirks this duty in favor of goofing off.
- Nice Hat: He wears a black baseball cap with the bill pointed backwards.
- Non-Action Guy: Boone has fewer combat skills than Sashi and Penn and often has to resort to running or hiding during dangerous battles.
- Ordinary High-School Student
- Part-Time Hero: He serves as the team's part-time wise man.
- Performance Anxiety: "Defending the Earth" reveals that he's scared of public speaking because he doesn't think he's smart enough to avoid embarrassing himself in front of hundreds of people.
- Smarter Than You Look: While he can be a hindrance he's also quite intelligent, especially when it comes to using the show's Fisher Kingdom setting to his advantage (singing a cheery Christmas Special song in order to make Penn's Santa Claus power work, behaving like a Literal Genie in order to get Rippen to waste his wishes, etc). He's also pretty eloquent, as evidenced by his speech at the end of "Defending the Earth".
- The Storyteller: Spontaneously narrates stories and scenarios when inspired. Said stories are often very strange.
- Why Did It Have to Be Snakes?: "Chicken or Fish?" reveals that he's terrified of water, which is unfortunate because the day's mission takes place in an underwater city.
- Voiced by: Alfred Molina
A part-time villain who also happens to be the heroes' art teacher, much to his chagrin. Cynical and grumpy thanks to his countless losses but also a threatening Determinator who gets the upperhand whenever the heroes underestimate him.
- Angrish: Frequently mutters this under his breath.
- Another Dimension: In "Mr. Rippen", it's revealed that he comes from another dimension.
- Arch-Enemy: He serves as one for Penn.
- Beard of Evil: Most of his transformations have this.
- Being Evil Sucks: Aside from the fact that he's constantly losing to Penn, a teenaged boy, his job also means he's stuck trying to please parents who barely care about him, and his job sometimes (albeit fairly rarely) causes conflicts of interest with Larry, about the only person he could consider a friend.
- Big Bad: The primary antagonist of the series, and Penn's Arch-Enemy.
- Cannot Tell a Joke: When Penn tells Rippen that he doesn't have a sense of humor he attempts to refute the claim by reciting an incredibly lame joke that leaves everyone staring at him in a mix of annoyance and pity.
- Character Tics: Grits his teeth whenever he's the slightest bit unhappy.
- Earn Your Happy Ending: Going to the Most Dangerous World Imaginable. There, he can be a full-time villain and be with Lady Starblaster. Larry and several others tagging along sort of puts a damper on it for him, but this surrogate family is far more loving than his actual family. As he says, it's still better than his old life.
- Even Bad Men Love Their Mamas: Definitely shows this in "My Mischievous Son", where just playing the role of an Enfant Terrible leads to Rippen sympathizing so much with his in-universe 'mother' that he basically surrenders the mission to stop her from crying. Comes with a shade of "Well Done, Son!" Guy, especially when he casually mentions that his own mother never showed him any kindness.
- Evil Brit: He speaks in a very British accent.
- Evil Counterpart: Penn is a part-time hero, Rippen is a part-time villain.
- Beyond that, Penn's parents love and are proud of him no matter what, give him advice, guide him if he does something wrong and kept the whole part time business a secret from him because they wanted him to have a normal childhood and don't force him until they needed to be saved. Rippen's parents on the other hand raised him to be evil, only compliment him if he does something worthwhile, mock him for his repeated losses to Penn rather than teach him how to be a better villain.
- He's also one to Sashi given they just want their parents to be proud of them and are overshadowed by their sibling, only Sashi's family is supportive.
- Evil Teacher: He is an art teacher when he's not a part-time villain, but he wants to become a full-time villain.
- Evil Cannot Comprehend Good:
- In "Cereal Criminals," when Penn followed through on his promise to give Rippen a good evaluation, Rippen thought he was "trying to make [him] feel small with your generosity."
- In "Where Dragons Dare," it never occurred to him that Blaze would want to beat Penn fair and square, without interference.
- Averted in The End of All Worlds when he's horrified at the four legged shark knocking Penn off a cliff and into the fiery abyss below after Penn saved him (never mind the shark was following his orders to begin with) and pulls Brock and Vonnie out of the MDWI. Also, see Heroic Sacrifice below.
- Evil Only Has to Win Once: He only needs one successful mission to be promoted to full-time villain.
- Fatal Flaw: Overconfidence. Despite his constant failures, he's always convinced his current scheme will succeed, which often leaves him careless or ignorant of the heroes' finding a way to win.
- Faux Affably Evil: Cheerfully mocks the heroes whenever he gets the upper hand, though he does occasionally have genuinely civil conversations with them instead.
- Freudian Excuse: He comes from a family of villains, where he's The Unfavorite compared to his full-time villain sister, Vlurgen. The only time he got any respect from his parents was when he trapped Brock and Vonnie in the Most Dangerous World Imaginable.
- Heroic Sacrifice: At the end of "The End Of All Worlds", when evil energy from The Most Dangerous World Imaginable threatens to rip apart all reality, he opts to go into said world to activate the implosion bombs needed to contain the energy.
- Hypocrite: In "Number One, Number Two", he mocked Penn for putting trust in others, yet he was shocked when his "real new number two" sold him out for the reward money.
- Ineffectual Sympathetic Villain: While his motives and actions are typically selfish, mean-spirited and ruthless, the above mentioned Freudian Excuse and his hilariously terrible life make it hard not to feel for Rippen a little.
- Irony: He thought trapping Brock and Vonnie in the Most Dangerous World Imaginable would allow him to become a full-time villain with ease. Instead, it just led him to experience repeated defeats at Penn's hands.
- Never My Fault: Several episodes show that Rippen blames Larry for all his defeats, despite the fact that most of the time, the fault lies with him.
- Nice Job Fixing It, Villain!: In "It's A Colorful Life", Rippen cruelly ditches the Drabs after he collects the last of the colored rocks, intending to win by himself. This allows Penn to convince the Drabs and Hues that they're Not So Different, causing them to band together to defeat Rippen.
- In the finale, Rippen stabs Penn, charging the third shard with enough evil energy to open the portal to the MDWI.
- Non-Standard Character Design: His greenish skin, yellow eyes, red pupils, and pointy ears make him look very out of place next to the other characters. Justified in that he isn't human, he's an alien from another dimension who came to Earth for his part-time villain career.
- Plot-Irrelevant Villain: Rippen is this in "The Ripple Effect". His goal in that episode is to convince the cutelings to move to a planet named Ploopiter and he's not responsible for the catastrophe that made them need to move from their home planet in the first place. Penn is the one who caused the trouble.
- Punch-Clock Villain: Thanks to only being a part-time villain. Rippen spends most missions trying to kill or otherwise injure Penn, but while they're off-the-clock he limits himself to insults and giving the boy bad grades.
- Red Eyes, Take Warning
- Skunk Stripe: Several, actually. He's delighted when he finds out that Lady Starblaster likes them.
- Throw the Dog a Bone:
- In "Cereal Criminals" he's deemed Teacher of the Month thanks to a positive evaluation from Penn, allowing him a better parking spot.
- In "Larry Manor", Penn decides to intentionally lose their mystery-solving contest after realizing how depressed Rippen is about losing to him all the time.
- The Only One Allowed to Defeat You: In "Hail Larry", when Larry, who was substituting for him, was about to succeed in the villain mission, Rippen zapped into the dimension and destroyed the axe that Larry needed to complete it. He did this because he was worried about Larry becoming the full-time villain instead of him.
- The Un-Favourite: Was this to his sister Vlurgen, who was praised by his parents for being a better villain.
- Underestimating Badassery: He refuses to consider Sashi and Boone as threats, despite them actually ensuring his defeat on a number of occasions.
- Unfortunate Names: In "Defending the Earth", Rippen is known as "Ugthar the Ugly".Rippen: No, that can't be my name.
- Villain Has a Point: In the finale, he semi-sarcastically believes Penn's parents must be proud of him and points out that not everyone has that. Simply put, he's right.
- "Well Done, Son!" Guy: His backstory in "Mr. Rippen" shows that he spent most of his young life trying to impress his parents— and that he still seems to crave their love and respect, even though they openly refer to him as a disappointment.
- Voiced by: Larry Wilmore
A cheerful part-time minion who has a separate job as the heroes' school principal. Being a multimillionaire, he doesn't really need either of his jobs but stays employed in order to spend time with Rippen.
- Affably Evil: He's genuinely friendly towards the heroes when he's not helping Rippen defeat them.
- Beware the Nice Ones: He throws Starblaster into a water vortex after she reveals that she never had feelings for Rippen and was only manipulating him for her own gain in "Lady Starblaster".Larry: No one betrays my bestie!
- Plus, in "Hail Larry", he came FAR closer to beating Penn, Boone, and Sashi than Rippen ever did. The only reason he wasn't successful was because Rippen zapped in at the last minute and destroyed the axe he needed to complete the mission.
- Born Lucky: In sharp contrast to Rippen, who can never succeed at anything. He's won dozens of lotteries, is rarely inconvenienced even in defeat while Rippen gets Humiliation Congas, and never loses his cheerful attitude while Rippen is constantly angry or depressed. It's even lampshaded:Rippen: How is it that you never get hurt!?
- Cloudcuckoolander: Doesn't seem to understand the concept of personal space and once mistook a Bat Out of Hell for a bird.
- The Dragon: He acts as this whenever he gets a form that's more powerful than Rippen's.
- Eccentric Millionaire: He's won 33 lotteries, and uses his money to fill his enormous mansion with insane and ridiculous things - like a roller coaster, a gift shop and a room that leads to a pit filled with snakes and bats.
- Evil Teacher: He is the principal of Penn's high school when he's not being Rippen's part-time minion. Though unlike Rippen, he's not a jerk when doing his job.
- Happily Married: To Madame President, as of "13 Big Problems".
- Goggles Do Something Unusual: Like Sashi's specs, Larry's glasses can project holographic images that inform him and Rippen about their missions.
- Ink-Suit Actor: He looks like a shorter version of Larry Wilmore, glasses and all.
- Kavorka Man: In "3 Big Problems", the Madame President seemed REALLY interested in him.
- Plus, in "Lady Starblaster", after the titular character betrays Rippen, she asks Larry to join her.
- Minion with an F in Evil: Larry's often too nice to be an actual threat, almost to the point of being a Spanner in the Works. Rippen describes him as "the most loyal but least evil minion ever".
- Motor Mouth: Has a fondness for lengthy anecdotes about his life. Even being turned into an incoherent zombie doesn't shut him up.Zombie!Larry: (growls and gurgles animatedly for several seconds)Rippen: Larry, your rants are even more annoying when I can't understand them.
- Nested Ownership: He's so rich that his butler has a butler.
- Number Two for Brains: Frequently screws up Rippen's plans.
- Phrase Catcher: "Check the spectacles."
- The Fool: He's won a couple dozen lotteries and is quite wealthy.
- The Pollyanna
- Punch-Clock Villain: Even moreso than Rippen, who does part-time villainy because he wants to be recognized as a real villain. Larry has no real interest in evil, is a perfectly nice - if somewhat off-kilter - guy outside of part-timing, doesn't even need the extra money (provided they get paid), and seems to only even do it because he's Rippen's only friend.
- Stepford Smiler: He really is happy most of the time but on the rare occasion when he isn't, he fakes a smile anyway.
- Talkative Loon: Loves telling long, rambling stories that don't go anywhere and are completely irrelevant to the situation at hand.
- Undying Loyalty: The reason why Rippen keeps him around. Larry even got trapped in The Most Dangerous World Imaginable with him when he went there to contain the evil energy coming from it.
The leader of the Unicorn Army. Muscular, boisterous, and ruthless, she won't hesitate to utterly destroy her opponents through brute force or a blindingly lethal rainbow blast.
- Achilles Bellybutton: Her bellybutton is her weakness, despite the fact that she has no clothing covering it, and a pretty prominent bellyring. You could attribute this to the same logic as the Unicorn engineers putting a giant, blinking "Please don't shoot." sign on their battleship's one weakness.
- Awesome Aussie: Female example. Speaks with a strong Australian accent, muscular and doesn't hesitate to get physical, brutally efficient.
- Bare Your Midriff: Her uniform's jacket is tied up across her chest, and she wears only a tank-top underneath.
- Boisterous Bruiser: Her voice will blow you away, as will her punches. She also laughs heartily right after explicitly telling Rippen and Larry she will extract information from them then kill them anyway with point-blank rainbows.
- Boobs of Steel: She's got a heavy focus on her upper body, in more ways than one.
- Good Scars, Evil Scars: On the side of her neck where it connects to her shoulders, with dots on either side inferring less-than-ideal stitching, and unquestionably Evil.
- Large and in Charge: As her name implies, her horn and physical appearance are MUCH larger than the other unicorn soldiers.
- Light Is Not Good: Her primary ranged weapon is rainbow blasts from her horn. Her uniform's insignias are in pastel rainbow colours. She and her army leaves no survivors, and the exceptions are left completely broken.
- Voiced by: Paul Reubens
From the Cereal Dimension.
A man made of milk who plans to flood the cereal crops with milk, turning them soggy and ruining the economy and primary food source of the dimension.
- Casual Danger Dialog: A benefit of his invulnerability is that he can hold conversations while being punched through the chest.Milkman: Didn't your mother ever tell you not to put your fist inside someone's chest?
- Catchphrase: As befitting a mascot for a product. His is "You drink up, now!"
- Con Man: In Season 2, the Milkman plays his role to Wrong Way/Rippen and Otis/Larry.
- Faux Affably Evil: He is disturbingly cheerful and polite, even while attempting to kill his enemies or causing mass destruction of valuable resources essential to economy and survival.
- Logical Weakness: Since he's made out of milk, he can be soaked up and trapped in a bottle, or even turned into butter. And his butter form is highly vulnerable to heat, which causes him to melt.
- Nigh-Invulnerability: His body is made of milk, meaning attacks go right through him without causing any harm.
- Nonstandard Character Design: The only Cereal World citizen with a monochrome color scheme and Black Bead Eyes.
- Not So Invincible After All: He's shown to be immune to physical harm, or getting shot with strawberry cereal via Sashi's "Agent Flaming-O" gun. Like actual milk, however, you can soak—or suck—him up, and capture him in a glass bottle.
- or as Season 2, turn him into butter.
- Terms of Endangerment: Frequently refers to everyone, including his enemies, as "friend". It's very obvious he's using it ironically.
- Voiced by: Adam West
From the Superhero/Supervillain Dimension.
By far the biggest supervillain of his dimension, Professor Evil Professor (or, correctly pronounced, "Professsorrr Evilll Professsorrr!") is ruthless, cunning, and just plain not a good person.
- Cain and Abel: The Cain to his brother, Captain Super Captain.
- The Corrupter: Enjoys turning heroes evil through a combination of mind control and manipulation.
- Evil Genius: He has a PhD in Evilness to prove it, too.
- Hypno Trinket: Wears a glowing medallion that hypnotizes anyone that looks directly at it.
- Knight of Cerebus: Has been the first villain on the show that has both betrayed his fellow villains and threatened to actually kill someone.
- Large Ham: He's voiced by Adam West. Really, it's to be expected.
- Pet the Dog: Always carries a pet turtle that he cares for. When he's arrested, he gives it to Captain Super Captain and asks him to take care of it.
- Voiced by: Sigourney Weaver
From the Planetary Conquest World.
A high-ranking Galactic Conqueror who enjoys destroying planets and solar systems.
- Alto Villainess: She's got a throaty voice that borders on raspy.
- The Baroness
- The Dragon: She serves a warlord named Count Destructo.
- Evil Laugh: A rather maniacal one at that.
- Galactic Conqueror
- Human Outside, Alien Inside: If her giant, snake-like tongue is any indication.
- You Gotta Have Blue Hair: Her hair has purple highlights.
Other Characters (Earth)
- Voiced by: Sam Levine
An elderly technician who's in charge of both the Odyssey and the part-time heroes. She's got some very strange habits but is ultimately a very capable boss.
- Ascend to a Higher Plane of Existence: Alongside Phil in the Grand Finale.
- Beauty Mark: She has a mole on her right cheek.
- Big Good: She maintains the dimensional gate and serves as a mentor to the younger part-time heroes.
- The Comically Serious: She usually acts very serious and speaks in a sort of monotone voice.
- Crazy-Prepared: To prevent people from killing her via her flower allergy, she's installed an Odyssey dispenser that's labelled "In Case of Flowers" and contains a miniature grenade.
- She's also been spying on Phil for decades, using a camera hidden is his best customer's beard.
- Crusty Caretaker: The irritable custodian in charge of the Odyssey. One of the many features she's added to it is a "Not-Welcome-Mat".
- Fusion Dance: Does this with Phil in the Grand Finale.
- Human Outside, Alien Inside: Implied at times. Aside from her claim to be over a thousand years old, when she shows a severe allergic reaction to some flowers, she states that her "internal organ" (singular) will eventually heal itself.
- Jerk with a Heart of Gold: With a temper best not provoked and a lack of kindness towards other, she is not the friendliest of people, but she is occasionally nicer or more thoughtful to the part-time heroes.
- Good Is Not Nice: She has dedicated her life to employing part-time heroes in order to protect the balance of good and evil in the multiverse, but is generally a sour, crabby woman.
- Paper-Thin Disguise: Wears a Boone costume (that shows her face coming out of his mouth) just so she can eat his mother's meatloaf.
- Really 700 Years Old: In "Lady Starblaster" she casually mentions that she's more than a thousand years old.
- Wrench Wench: Maintains the dimensional gate.
- Voiced by: Gary Cole
Penn's father and a former part-time hero. He's currently trapped in The Most Dangerous World Imaginable alongside his wife, Vonnie.
- Action Dad: Part-time hero and Penn's father.
- Amazingly Embarrassing Parents: Brock and Vonnie unintentionally embarrass their son by mentioning things like the rash on his bottom while his friends are watching.
- Battle Couple: With Vonnie. They are Happily Married with a son, are (or now, were) part-time heroes, and are now surviving being trapped in The Most Dangerous World Imaginable together.
- Boisterous Bruiser: "Baby-Pocolypse" has him laughing and yelling insults while fighting a giant spider.Brock: Keep it up! I will eat ANOTHER one of your eggs!
- Bruiser with a Soft Center: He's an experienced part-timer hero whose not afraid to kick butt, but he's also a Nice Guy who deeply loves his wife and son.
- Calling Your Attacks: Fond of making up attack names that fit the opponent he's fighting."CONIFEEEER KICK!"
- Casual Danger Dialog: He and Vonnie have mastered the art of this thanks to being trapped in a world of non-stop danger; all their MUHU conversations with Penn involve them giving him advice or discussing mundane topics while fighting monsters or defusing bombs.
- Happily Married: Brock loves his wife, and they both work together as a skilled team.
- Heroes Want Redheads: Happily Married to part-time hero, Vonnie.
- Nice Guy: Brock is brave and kind.
- Part-Time Hero: Before he got trapped in another dimension known as the Most Dangerous World Imaginable.
- Voiced by: Lea Thompson
Penn's mother and a former part-time hero. She's currently trapped in The Most Dangerous World Imaginable alongside her husband, Brock.
- Action Mom: Part-time hero and Penn's mother.
- Amazingly Embarrassing Parents: If Penn's friends are with him, it's likely that his parents will say something that embarrasses him in front of them.
- Battle Couple: With Brock. They are Happily Married with a son, are (or now, were) part-time heroes, and are now surviving being trapped in The Most Dangerous World Imaginable together.
- Casual Danger Dialog: She and Brock have mastered the art of this thanks to being trapped in a world of non-stop danger; all their MUHU conversations with Penn involve them giving him advice or discussing mundane topics while fighting monsters or defusing bombs.
- Fiery Redhead: Vonnie shows a lot of strength and fury when fighting anything that the Most Dangerous World Imaginable throws at her.
- Happily Married: Vonnie loves her husband, and they both work together as a skilled team.
- Nice Girl: While passionate and ferocious when dealing with foes, she is very kind and loving.
- Part-Time Hero: Before she got trapped in another dimension known as the Most Dangerous World Imaginable.
- Voiced by: Sam Levine
A man who's in charge of both the Fish-Stick-on-a-Stick restaurant and the part-time villains.
- Ascend to a Higher Plane of Existence: Alongside Phyllis in the Grand Finale.
- Beauty Mark: Has a mole above his right cheek.
- Distaff Counterpart: As his name implies, he's a male version of Phyllis.
- Evil Counterpart: To Phyllis. While she supports the part-time heroes, Phil supports the part-time villains. They even have a mole in different places.
- Fusion Dance: Does this with Phyllis in the Grand Finale.
- The Stoic: His expression never changes.
- Stupid Evil: He actually hired Penn as a part-time villain in "The Ripple Effect" despite his status as a part-time hero, believing his flimsy answers about his past evil experience, and even letting Penn zap into the Least Dangerous World Imaginable as himself without suspecting anything.
- Villains Out Shopping: He's on Penn's Uncle Chuck's bowling team.
- Voiced by: Lenny Venito (Uncle Chuck), Rosie Perez (Aunt Rose)
Penn's aunt and uncle, who act as his guardians while Brock and Vonnie are trapped in The Most Dangerous World Imaginable.
- A Day in the Limelight: "The QPC."
- Black Sheep: They're ordinary people rather than part-time heroes like Penn and his parents.
- Joisey: Aunt Rose has this accent.
- Odd Friendship: Uncle Chuck has this with Phil, being his best customer at Fish Stick On a Stick and a member of his bowling team.
- Skewed Priorities: In "The QPC", they think Penn getting a tandem massage with their pet chinchilla is more important than Penn doing his job.
- A Day in the Limelight: In "The Chinchilla". He even helps Penn save the day!
- A Dog Named "Dog": Simply called "The Chinchilla".
- Amplified Animal Aptitude: Displays this at times, such as in "The Ripple Effect", when it stood guard over the outside of the house, and in "The QPC", where it was able to operate a freeze gun.
- Freudian Excuse: Its bad temper is most likely a result of Uncle Chuck and Aunt Rose constantly using Baby Talk around it, and dressing it up in various little outfits.
- Killer Rabbit: Surprisingly vicious at times.
- Spell My Name with a "The": Always referred to as "The Chinchilla".
- Voiced by: Lauren Lapkus
A background girl. According to Sam Levine, she will make more appearances on the show, possibly hinting that she might have a bigger role.
- Ascended Extra: She is slowly becoming this, having a few noticeable appearances in "The Princess Most Fair" and "Lady Starblaster".
- Everything's Cuter with Kittens: Her art project in "The Princess Most Fair" is a picture of a white kitten.
- Last Minute Hookup: She enters into a relationship with the class president in the Grand Finale, at the same time acknowledging that Penn never really showed any actual interest in her.
- Meganekko: She wears pink glasses that accentuate her doe-eyes.
- Purple Eyes: They're periwinkle.
- Ship Tease: She sighs and giggles after Penn dances with her in "Lady Starblaster".
- Her art project in "Trading Faces" was a picture of how she envisioned their wedding would go.
Other Characters (Alternate Dimensions)
- Voiced by: Adam West
From the Superhero/Supervillain Dimension.
One of the most iconic superheroes in his realm, Captain Super Captain (or, properly pronounced, "Captaiiinnn Superrrr Captainnnn!") is your standard do-gooder with flight, super-strength, and laser vision, with the added bonus of being a highly skilled electrician.
- Adam Westing: But of course!
- Barrier Warrior: His main ability is summoning electrified shields that can be used to either deflect attacks or bash enemies.
- Big "NO!": Prone to this. Attempts to teach Penn how to do a proper one in "I'm Still Super!"
- Cain and Abel: The Abel to his brother, Professor Evil Professor.
- The Engineer: He's a very skilled electrician, capable of rewiring a giant robot suit on a dime.
- Flying Brick
- Large Ham: As befitting someone voiced by Adam West.
- Voiced by: Beau Bridges
From the Dinosaur Cowboy Dimension.
The sheriff of the town the Part-Timers find themselves in—if only because he hasn't been formally booted from his position yet. Well past his prime, Briggs finds himself struggling to keep the law and proving to both the town and himself that he's still got it.
- Cool Old Guy: In spite of his age and his failing body, he still has his tricks.
- Glory Days: He used to be quite the sheriff, the stuff of Western legend. Now those days are just that: stories of a man from long ago.
- How the Mighty Have Fallen: He used to be popular and beloved. These days, the town is just this close to running him out of town—they've already protested and asked him to just leave on his own.
- Scatterbrained Senior: His age and Amber's disappearance have taken quite a toll on him; when the heroes revisit him in "Amber" he's unable to remember who they are.
- They Call Me Mister Tibbs: Insists on being called "Sheriff Scaley Briggs".
- Voiced by: Olivia Holt
From the Dinosaur Cowboy Dimension.
A quick-witted rustler who also happens to be the daughter of Sheriff Scaley Briggs.
- Antagonistic Offspring: Her father's a sheriff, she's a rustler.
- Dark Action Girl: Makes her debut by effortlessly incapacitating Sashi in a matter of seconds.
- The Dragon: Hired to keep Sashi from escaping.
- Friendly Enemy: To the extent that she offers Sashi food after capturing her.
- The Runaway: You don't exactly get to stay in town once you decide to become an outlaw. She ends up going home after her deputization.
- The Rustler: Though she makes a living from stealing dinosaurs rather than cattle.
- "Well Done, Daughter!" Girl: Became a criminal to prove to her dad that she's capable of keeping up with him. He ends up deputizing her at the end of the episode.
- Voiced by: Maria Bamford
From the Giant Monster Dimension.
The president of a city nation located right next to an island inhabited entirely by monsters. She's determined to ignore what a precarious situation she's in.
- Cloudcuckoolander: She desperately wants to believe that the neighboring monsters are friendly and tries to make excuses for their various misdeeds.President: These could all be accidents! Combined with... convenient misunderstandings.
- The Cuckoolander Was Right: She's completely right about the monster attacks being accidental.
- Happily Married: To Larry as of "13 Big Problems".
- O.O.C. Is Serious Business: Her cheerful demeanor disappears when Rippen activates the Buster Bomb before the monsters clear the city.President: You fool! You've doomed us all!
- Skewed Priorities: During the scene where the monsters "destroy" the city she comes to the realization that she's been pronouncing "bologna" wrong all her life. She then becomes frustrated that she's thinking about something so mundane at such a crucial moment.
- Voiced by: Sean Astin
From the Dragon Dimension.
A charming and exceedingly popular Flight School cadet who Penn has to compete against in order to graduate at the top of their class.
- The Ace
- Broken Ace / Fallen Hero: By Season 2, the attack of the unicorns and the effortless destruction of all of the Dragon's bases except for Wingfire Academy has completely demoralized Blaze, to the point where in the span of a few weeks he has become seriously overweight, lazes around all day, and binges on soda, frozen pizza, and cooking shows.
- Big Eater: Becomes one after his Heroic BSoD It's... not pretty.
- Cavalier Competitor: He's serious about beating Renegade/Penn (who he considers a Worthy Opponent) but isn't particularly hostile about it.Blaze: Good luck, Renegade.
Penn: (irritated) I will not be psyched out by your good sportsmanship.
- The Charmer: The other cadets adore him and it takes about three seconds for him to win both Boone and Sashi over.
- Cynical Mentor: Becomes one in the second season.
- Heroic BSoD: Has one in the second season, when the unicorns attack and utterly destroy one of the first dragon bases.
- Our Dragons Are Different: He may have hair and a humanoid body structure but he's still very clearly a dragon, scales and all.
- The Rival: To Renegade and, by extension, Penn.
- Ship Tease: With Sashi. She ends up being the reason he comes back from his Heroic BSoD in season 2.
- Sunglasses at Night: A justified case. His aviators may look cool but their actual purpose is to protect his eyes during flights, much like actual pilot-aviators.
- Third-Person Person
- Voiced by: Rena Strober
From the Plant Noir Dimension.
An enigmatic lounge singer who's searching for her brother, Fern — an actual fern, he's adopted.
- The Chanteuse: A tribute to the classic Film Noir types. Penn and Sashi attend one of her performances at a local lounge.
- FaceHeel Turn: She takes on a much more dramatic, pivotal role in the events of Season 2.
- Hello, Nurse!: Penn is infatuated with her from the moment they first meet.
- Lady in Red: Both literally and figuratively.
- Mysterious Woman: Penn thinks she has something to do with the city's crime syndicate because mysterious female clients always end up being plot-relevant in noirs. In the end his hunch turns out to be wrong; Orchid really was just looking for her brother.
- Ends up Subverted in Season 2, when she turns out to be the one who kidnapped Boone and engineered the entire plot to steal the soil company's fortune, in an attempt to fund her scat singing album.
- Nonindicative Name: Her mismatched name is a reference to a William Shakespeare quote — "A rose by any other name would smell as sweet."Orchid: The name's Orchid.
Penn: But... you're a rose.
Orchid: Nothing gets past you, does it?
- Plant Person: An anthropomorphic rose.
A Pirate and her talking boat, both named Maria, a fact that is frequently lampshaded.
- Almost Kiss: With Penn in "Mr. Rippen".
- Chronic Backstabbing Disorder: First, she did it because she didn't want Penn betraying her first. Then she did it because she's a pirate.
- Lovable Rogue: Pirate Maria is unquestionably a swashbuckler: she steals, she manipulates, she double-crosses as soon as it becomes convenient for her. Still, she hasn't outright killed Penn, was at least willing to work with others until her original crew betrayed her, and did honestly mean that she liked Penn—even though she was using the hug to tie him up and escape with the treasure.
- Ship Tease: Frequently, with Penn.
A ghost of a comedian from the 1930s that the gang has to save.