Voiced by: Jeff GarciaAfter disregarding a bunch of warning notes in Jimmy's lab, Sheen ends up piloting Jimmy's new rocket into space and crashing onto planet Zeenu, where he ends up praised by the inhabitants as a hero.
- Adaptation Personality Change: Being away from Earth has turned him from a nerdy, hyperactive kid into a lazy, irresponsible and obnoxious prick.
- Character Exaggeration: Sheen used to be a nerdy, hyperactive kid in the old show, but here his redeeming qualities and serious traits have been erased, turning him into an obnoxious, self-centered moron.
- Idiot Hero: He's the main protagonist and is a complete idiot.
- Idiot Houdini: Sheen never gets punished for all the bad things he does and never gets called out on it.
- Insane Troll Logic: He forgets everything he used to know in the original series and now makes stupid claims.
- Never My Fault: He frequently blames Mr. Nesmith for the mistakes and misdeeds he makes.
- Nice Job Breaking It, Hero!: He always puts Zeenu in danger and he is the one who caused Dorkus to pursue him with never ending vengeance. Did we also mention that he stole Jimmy's rocket and back on Earth he's probably getting a lot of grief because of it?
- Unsympathetic Comedy Protagonist: His Flanderization puts him into this category perfectly.
Voiced by: Bob JolesA chimpanzee from Earth who ended up on Zeenu after being sent into space and crosses paths with Sheen. He's more interested in fixing Sheen's rocket so they can go home, but his progress is often delayed by Sheen's antics.
- Apes in Space: He was part of the space program and crash landed on Zeenu.
- Butt-Monkey: He frequently suffers because of Sheen's selfish and misguided decisions.
- Deadpan Snarker: He tends to make dry remarks about Sheen's dim-witted assumptions and ideas.
- Expy: He seems to be Jimmy if he was more responsible, patient, sensible and not-so irritable.
- Nice Hat: He wears a red pom pom hat.
- Only Sane Man: He, Aseefa and Dorkus are often the most rational and realistic of the cast.
- Insistent Terminology: He often has to remind Sheen that he is a chimpanzee and not a monkey.
- Talking Animal: He is a talking chimpanzee.
Voiced by: Rob PaulsenA slug-like alien who looks like Carl and Sheen befriends after ending up on Zeenu.
- Cowardly Sidekick: Just like Carl.
- Meaningful Name: Doppy's name is most likely a reference to him looking like Carl.
- Suspiciously Similar Substitute: He bears significant resemblance to Carl and even has the same voice. Sheen even is shocked by this when he first encounters him at the end of the pilot.
- Interestingly enough, Carl was going to be part of the show, but a Nick executive changed it to Doppy, Carl's alien double.
Voiced by: Fred TatascioreThe ruler of Zeenu who blindly trusts Sheen with important tasks, unaware of the idiot the human really is.
- Henpecked Husband: He is shown to be easily intimidated by his wife in "Nightmare Sheenario".
- Large Ham: He tends to speak loudly and with a lot of flare. Justified in that he is royalty.
- The Napoleon: He's much shorter than your average Zeenuian.
- The Noseless: It is mentioned in "QuaranSheen" that he used to have a nose, but removed it because of his extreme germophobia.
- Some Call Me "Tim": He is addressed as "The Emperor" because many people have trouble pronouncing his actual name.
- Top-Heavy Guy: He has a large chest and spindly legs.
Voiced by: Candi MiloThe Emperor's daughter, who has a crush on Sheen, much to his dismay. She has a habit of licking him with her gigantic tongue, an action which she refers to as "raffenhoffering".
- Abhorrent Admirer: Sheen is clearly not interested in her. The only reason he isn't upfront about disliking her is because he knows it might anger the Emperor.
- Affectionate Nickname: She's prone to calling Sheen "Sheeny-Weeny".
- All Love Is Unrequited: It never gets through Oom's thick skull that Sheen doesn't like her, no matter how many times he tells her.
- Brainless Beauty: One of her faces is beautiful. The other one is hideous.
- Genki Girl
- Huge Schoolgirl: She is extremely tall.
- Lecherous Licking: Her way of showing Sheen affection.
- Stalker with a Crush
- Two-Faced: She has two different faces, one that is somewhat attractive and one that is homely and has oversized lips.
Voiced by: Soleil Moon FryeA warrior girl that Sheen becomes attracted to.
- Action Girl
- Adorkable: Whenever she's around Sheen and trying to ask him for a favor.
- Expy: Aseefa seems to take Libby's place as Sheen's significant other, but acts more like Betty or April.
- Gasshole: Aseefa becomes this after losing her roove in "Feeling Roovy". A roove is an animal living in Aseefa's throat that which enables her species to yodel. Without it, she belches constantly.
- Green-Skinned Space Babe: She's a very attractive girl with blue skin.
- Lady of War: She's very passionate about fighting.
- Only Sane Woman: She, Nesmith and Dorkus are the only rational and realistic characters of the show.
- Ship Sinking: For some reason, Sheen seems to have pretty much forgotten about Libby.
- You Gotta Have Blue Hair: Like her skin, her hair is blue.
Voiced by: Jeff BennettThe main villain of the series. After Sheen accidentally destroyed his house in the pilot, Dorkus has ever since been hellbent on finding a way to get rid of Sheen or at least expose to the Emperor the moron Sheen really is.
- Bald of Evil: When not wearing his hood, he is shown to be bald.
- Big Bad: He is the show's main antagonist.
- Expy: He acts a lot like King Goobot.
- Ineffectual Sympathetic Villain: None of his plans to get rid of Sheen work and he tends to suffer humiliating injuries because of them.
- In the Hood: He wears a shroud.
- Oh, Crap!: Prone to saying "Oh, grock" when he realizes something bad is about to happen to him.
- Unknown Rival: Sheen is completely oblivious that Dorkus hates him and wants to get rid of him.
Voiced by: Thomas LennonDorkus' main lackey, who is essentially a flying winged orange creature with one eyeball and a mouth.
- Cephalothorax: He's a head with limbs, but no body.
- Cyclops: He only has one eye.
- Elmuh Fudd Syndwome: He often pronounces L's and R's as W's.
- Expy: He seems to be one for Ooblar.
- Number Two for Brains: He isn't much help to Dorkus, though he's usually more eccentric than outright stupid.
Voiced by: Jeff BennettA minor recurring character in the series.
- Defeat Means Friendship: He actually battled against Sheen in the pilot, but is shown to be on good terms with him in later episodes.
- My Nayme Is: His name is "Bob" spelled with three B's.
- Simpleton Voice: He has a moronic-sounding voice, which is similar to the voice Jeff Bennett used for Big Billy of the Gangreen Gang fom The Powerpuff Girls.
- Tiny-Headed Behemoth: He's a huge muscular guy, but his head is comically small.