The titular character, he's a Legacy Character who fights comic book type monsters and Mad Scientists with an array of gadgetry and good old fashioned fisticuffs. Works for O2STK, the Organization 2 Secret To Know.
- Big Brother Instinct: Stated himself that thinks of Wendy like a little sister.
- Everyone Calls Him "Barkeep": He is only ever addressed by variations on his title and job description, such as "Middleman", "MM", "Double-M", "Wendy's Boss".
- Disco Dan: He acts like a Golden Age square jawed super hero.
- No Name Given: He never gives out his real name. Even under the effects of a truth gas, all he'll divulge is that he shares the same name as his father.
- Star-Crossed Lovers: With Lacey.
The POV character, she was a temp working at A.N.D. Labratories when a genetic abomination reminiscent of a hentai tentacle monster attacked her and the Middleman stepped in. Now she's his apprentice/sidekick/partner.
- Action Girl: After her training with Sensei Ping.
- Birds of a Feather: With Tyler.
- I Have Many Names: Lacey calls her "Dub-Dub" while the Middleman calls her "Dubbie." Tyler calls her "Dubs" and Noser always uses her full name. Ida uses a variety of sarcastic and/or insulting nicknames.
- Jumped at the Call: Her reaction to the knowledge that ghosts exist? "Oh cool!"
- "Cool!" is also Wendy's reaction to Zombies. And Vampires, and... you get the point.
- Refused the Call: At first. But it was mostly due to The Middleman and Ida framing her for the destruction of her last workplace that freaked her out. But then Ben decided to break-up with her and film it and the rest is history.
- Her accepting the giant monster's existence and leaping at it with a letter opener instead or running and screaming is what got her the job in the first place. She jumped at the call before there was even a call.
- Orphan's Plot Trinket: Her dad's lighter (though she's technically not an orphan).
- Spicy Latina: Invoked by Middleman '69, who refers to Wendy as "a hot and spicy Spanish girl."
- Technical Pacifist: Wendy hates guns, but has a bit of a geeky affection for the sci-fi weapons the Middle organization uses. She also loves training with Sensei Ping, and she frequently protests the Middleman's tendencies toward violence. But she had no problem whatsoever beating a venomous Peruvian Pike to death.
- Unfazed Everyman: Her reaction to the lab explosion is how she got the job.
- You Need to Get Laid: Well, at least Lacey thinks so.
The Middleman's robot assistant stuck in the form of a snarky middle-aged schoolmarm. Is constantly saying that Wendy Watson is a stoner.
- Disney Death: The one from the series' first half actually does die, but O2STK promptly sends an identical replacement.
Wendy's roommate in their illegal sublet, she's an animal rights activist as well as another young, photogenic artist. She's also got the hots for the Middleman.
- Granola Girl: A fairly sympathetic example.
- Missing Mom: Dr. Barbara Thornfield, MD, PHD.
- Star-Crossed Lovers: With the Middleman, but she has no idea why.
- Stuffed into the Fridge: In the unaired 13th episode and graphic novel 'Doomsday Armageddon Apocalypse', Lacey is in the final stages of T-cell polymphocytic leukemia. Manservant Neville chose to punish the Middleman by giving Lacey this disease because it is the same disease which claimed the life of the other woman the Middleman loves, his mentor-and-prior Middlewoman Raveena Rao.
- Two Lines, No Waiting: Usually there's a A-plot with MM and WW and a B-plot with Lacey and Noser/Pip/someone else. Sometimes they converge.
- The Dreaded: Noser's talent and reputation as a ventriloquist are so great that the mere mention of his name causes one contestant in a competition to drop out, leave and quite possibly quit competing all together.
- Informed Ability: Not only his guitar playing skills, but his skills as a ventriloquist.
- Old Shame: His childhood career as a ventriloquist.
- The Pirates Who Don't Do Anything: Noser spends an awful lot of time not playing the guitar. He also has an incidental sideline in not riding a motorcycle, and an entire episode built around his not being a ventriloquist.
- Waxing Lyrical: He loves speaking in song lyrics.
A reformed succubus who works as a fashion designer and fronts a modeling agency, she helps MM with mystical problems.
- Dark Is Not Evil: The whole point of her fashion agency actually. It gives Succubi and Incubi a place to work and get reformed like she did.
- He Who Must Not Be Seen: Though mentioned a lot, he's seen in a total of one episode.
A prior candidate for the Middleman's apprentice, instead he met Wendy, forgot her with two day amnesia, then met her again and became her boyfriend.
- Easy Amnesia: Knocked on the head once and has two day amnesia. Yeah, just go with it.
- Missed the Call: His roommate mislaid his job offer letter.
Interrodroid 3000 through 7000A training robot that helps around the Middleman HQ.
- The Chew Toy: It tends to get its head ripped off. A lot.
- Badass Preacher: In the Mirror-Middleverse.
- Contemplate Our Navels: His one man act was called "Hey, Mr. God, What About Me?"
- Jerkass: A really, really big one, and a plagiarist on top of that.
The CEO of FATBOY Industries, which makes everything from coffee to ice cream to the uMaster, a virtually featureless cube that just happens to be the cool gadget that every young, creative artistic type just has to have.
- A God Am I: The Doomsday Armageddon Apocalypse.
- Bland-Name Product: The uMaster, which is treated as a synthesis of every cool i-gadget Apple has ever made (but only to the extent that everyone has to have one, as we are never shown what, if anything, the uMaster actually does.)
- Corrupt Corporate Executive: Maybe. In the altUniverse, he was good, so he might be evil in this universe. Confirmed by the Doomsday Armageddon Apocalypse. He ends up very nearly taking over the world.
- Evil Is Hammy: Mark Sheppard has way too much fun at the live reading, even overacting his death.
- Ink-Suit Actor: The comic incarnation of the character was very different to the TV version, but was deliberately drawn to resemble Mark Sheppard long before the chance to actually cast him came along.
- Well-Intentioned Extremist: His plan to become a Living God is environmentally motivated.
BenWendy's boyfriend of over a year, breaks up with her for a film school project.
- Jerkass: Granted he feels terrible about the whole "breaking up with Wendy for a project" thing at first, he still did something so selfish in the first place and later posted it online.
- True Art Is Angsty: The reason he breaks up with Wendy; his professor didn't think he had enough pain in his life.