The main character, a mouse from Nebraska. He comes to live with his cousin in Washington D.C. after his mother, father and all of his brothers and sisters are killed by exterminators. His simple country ways and gentle nature often leave him at a loss in the hustle and bustle of his fellow critters in the capitol.
- Actual Pacifist
- Beware the Nice Ones: His speech near the end of Of Thee I Sting shows signs of this.
- Break the Cutie: Watched his own family get gassed to death, had nightmares and a PTSD reaction when the capitol was gassed, thought he nearly killed a cat in one episode and was nearly murdered by drug dealers in one. So yeah, he's a Woobie all right.
- Chick Magnet: In "If Loving You Is Wrong", he gets attacked by a bunch of female hamsters and smothered with kisses. Miko also falls for him pretty quickly.
- Country Mouse
- Deadpan Snarker: He has an extremely dry sense of humor for All-Loving Hero of the show.
- Friend to All Living Things: He is very kind to the roaches and even to the cats.
- The Heart
- Heartwarming Orphan
- The Leader
- My God, What Have I Done?: Max starts crying when he thought he killed President Cat in A Little Romance.
- Naïve Newcomer
- Nice Guy
- Nice Hat
- Nice Mice
- Only Sane Man
- Sensitive Guy and Manly Man: Sensitive guy to Jammet's Manly man.
- Tender Tears
- Too Good for This Sinful Earth: Subverted, he nearly died twice (first from smoke inhalation, second time from drug overdose) but survived both times.
An uncouth, somewhat overweight rat who lives in the White House and finds himself with Max foisted upon him as a roommate. He is rude and crude but has Hidden Depths and is quite protective of his friends, despite often selfishly exploiting them and unthinkingly mistreating them.
- Anti-Hero: Type IV - V
- Comedic Sociopath
- Deadpan Snarker
- Fat Bastard
- Hair-Trigger Temper
- Heel Realization: He has a particularly heart-wrenching one in "Opie's Choice," when he sees what Opie's home life has become like since he got him addicted to Pep-Ups.
- Jerk with a Heart of Gold: Also a Jerkass Woobie.
- The Lancer
- Large Ham
- Nice Hat
- Sensitive Guy and Manly Man: Manly man to Max's Sensitive guy.
- Took a Level in Badass: The scene in "Opie's Choice" when he fearlessly faces down a couple police dogs.
- You Dirty Rat!: Subverted, he's somewhat of a Jerkass Woobie.
Max's cousin and (apparently) only living relative. She's an extremely opinionated social activist type.
A former lab rat with big glasses and male-pattern baldness, always seen in a gaudy Hawaiian shirt. He's Max's main friend other than Jammet, and has a tendency to randomly (albeit harmlessly) explode due to the experiments that were done on him.
- Absent-Minded Professor
- The Chew Toy
- Cloud Cuckoolander
- Disney Death: Has one in The Lady Doth Protest Much.
- Ditzy Genius
- Made of Iron
- No Indoor Voice
- The Smart Guy
Jammet's mother and the unofficial matriarch of the White House's rodent population. She is blunt and sarcastic, and doesn't hide the fact she prefers the polite, sweet, good-hearted Max over her gluttonous, cretinous son (but she still loves him).
- Anti-Hero: Type III
- Deadpan Snarker
- Jewish Mother: Subverted
- Smoking Is Cool
- The Snark Knight
- Team Mom: Sort of.
A jive-talkin', hip and modern cockroach. He becomes fast friends with Max after rescuing him in the first episode, and is generally one of the nicer characters.
One of two villainous cats living in the White House. Presumably he's the First Pet of (then) President George George. His name comes from the fact his nametag simply says "P" (for "Presidential"). A brutish, violent beast, he kills Jammet's friend Felix, whereupon he essentially becomes Jammet's arch-enemy.
- Ax-Crazy: With the exception of his fellow cat, he basically viciously attacks anyone and anything that gets near him, even humans.
- The Dreaded: Except for when he's bandaged up with his legs in casts, everyone is terrified of him and he is portrayed as a almost Lovecraftian horror of nature.
- Cats Are Mean
- Those Two Bad Guys: With the V.P. Cat.
- We Can Rebuild Him: After Max almost kills him, he returns all bandaged up. Particularly his head. It's eventually revealed, when he heals, that the vet installed a metal skullcap in his head which allows him to smash through walls and doors by headbutting them, making him twice as dangerous.
The second of the two evil cats, although his heart isn't in it as much as his partner. He would appear to be (then) Vice President Dan Quayle's cat, and is consequently modeled after his owner.
- Cats Are Mean: He tries, but can't quite succeed. He eventually gives up trying to be evil, undergoing a HeelFace Turn.
- Harmless Villain
- Ineffectual Sympathetic Villain
- Minion with an F in Evil
- No Celebrities Were Harmed: He's modeled on (then) Vice President Dan Quayle.
- Suddenly Voiced: For almost the entire series, he, like the P. Cat, never speaks, except to growl, snarl and meow. Eventually though he begins speaking out of nowhere and is quite eloquent and intelligent. He spoke three times, but in An Embarassment of Roaches, He spoke like Orson Welles.
- Those Two Bad Guys: With the P. Cat.
- Vice-President Who?
A jittery, insane squirrel who is friends with Jammet. He suffers a severe drug addiction thanks to Jammet getting him hooked on caffeine pills called Pep-Ups, and Jammet is often quite mean to him until realizing just how badly he's ruined Opie's life.
- Cloud Cuckoo Lander: Although how much of it is due to his Pep-Up addiction and how much of it is due to his natural personality is up for debate. Among other things, he claims he's "building a DC-10 out back."
- Drugs Are Bad: As demonstrated in his Very Special Episode.
- Functional Addict: At first. But...
- Addled Addict: The longer he goes, the more bizarre, selfish, mean and insane he becomes, increasingly unable to function at home or in public.
- Heel Realization: When he almost leaves Max to die.
- Keet: Due to his addiction to Pep-Ups, he's balls-to-the-wall hyperactive, amazed and enthusiastic about literally everything, even his own screwups.
Another friend of Jammet's, a fast-talking mouse. Like Opie, Jammet is often quite mean to him. He ends up being eaten by the P. Cat not long after he's introduced, making Jammet regret his harsh treatment of Felix and swear revenge.
A mouse from Japan who is the daughter of a visiting Japanese mouse official. Max becomes smitten with her.
- Nice Mice
- Weakness Turns Her On: Could be the reason she french kissed Max in A Little Romance.
- Yamato Nadeshiko