The Flesh: He's super strong and super naked!
- The Big Guy: The muscle of the group.
- Catchphrase: "Ouchies" whenever he suffers from Amusing Injuries.
- Dumb Blonde: A male example. The least intelligent member of the team.
- The Hero: Probably. He's mentioned first in the opening titles.
- Innocent Fanservice Guy: A naked muscleman who's evidently just too dumb to know any better.
- Manchild: He's as mature as a 5 year old. Which might explain why he's always naked.
- Naked People Are Funny: He never wears clothes for some reason. Seeing as he's an action figure, he can get away with it.
- Super Strength: He's super strong and super naked.
Thunder Girl: She flies like thunder!
- Flight: Her Power and the only one apparently.
- Leitmotif: One she sings herself, to a John Williams-esque tune, while flying.Thunder Girl! Flying like thunder! How other people must wonder, what it's like to be me!
- Non-Indicative Name: Despite her name, she doesn't Shock and Awe, though (Granted thunder is simply the loud booming noise that accompanies lightning).
- The Smurfette Principle: The only female lead on the show. Especially with the only other lead being Quarky.
- Women Are Wiser: Of the heroes, she is usually the smartest. Granted this is an extremely low bar and she's definitely not as above her male counterparts as she'd like to believe.
Stinky Diver: A former naval commando with an attitude as bad as his odor!
- Badass Normal: He has no superpowers, but can still help the team.
- Blood Knight: Sometimes. Certainly more violence-happy than the rest of the League.
- Dark and Troubled Past: He's had two events that have haunted his life. The first is when he failed to save his brother, Stench, from a flushing toilet. He was about to jump, but was afraid his wallet would get wet, and as a result, he was too late to save Stench. The second is when his own mother sold him out to the enemy in the Gulf War (for the money, of course).
- Iconic Item: His spear gun.
- Jerk with a Heart of Gold: He's pretty abrasive as the opening implies, but he's definitely one of the good guys. He also tends to insult the League almost as much as the Mayor and the Chief do, but "Armageddon Outta Here" and "Turkey of Terror" shows that he cares for them deep down.
- What the Hell Is That Accent?: His accent bounces between British and Australian. Naturally, this gets lampshaded by the Narrator in the anthology spin-off.
Meltman: With the power to ... melt!
- All Love Is Unrequited: He has an obvious crush on Thunder Girl, who unfortunately for him, doesn't return his affections.
- The Heart: The nicest member of the group, besides maybe Flesh.
- Kaiju: One episode has him become a giant known as Mega Meltman (portrayed by a guy in a Meltman costume).
- Lovable Coward: He's cowardly, but nice.
- Non-Action Guy: Would rather not be doing anything death-defying, strenuous, or even remotely dangerous. He usually ends up being thrown into the action accidentally.
- What Kind of Lame Power Is Heart, Anyway?: He has power to melt which he never uses.
- You, Get Me Coffee: The other members of the Action League often assign him to get them snacks, including sodas, pizza, and donuts.
- Blue Is Heroic: He wears a dark blue suit.
- Catchphrase: Tends to say "Blast it" when displeased (which is to say, all the time).
- Da Chief: It's in his name.
- Large Ham: His volume switch seems to consist of "loud" and "louder".
- The Leader: Non-action example; he's the smartest member of the team and the one who sends them out on their missions.
- Mentor Archetype: Kind of parodied. He tries, but they never listen.
- No Indoor Voice: Even at lower volumes, he usually just sounds like he's yelling more quietly.
- Only Sane Man: Saddled with the frustrating task of keeping the team focused and not running around like idiots (well, even more like idiots). It's no wonder he never stops yelling.
- Surrounded by Idiots: See Only Sane man above.
- Token Minority: Essentially subverted. The Chief is the only recurring African-American character on the show but nothing is ever made of it.
Bill the Lab Guy
- Catchphrase: Two."There's nothing I can do" and "Oh no, I was afraid of this.".
- Dull Surprise: Always speaks in a dead monotone.
- Papa Wolf: In "Big Baby", when Stinky Diver wants to destroy Big Baby, Bill objects, telling him that Big Baby is a rare creature to be studied, not destroyed. When The Chief and Thundergirl tell him that Big Baby has captured his daughter, Quarky, Bill snaps and wants to destroy Big Baby.
Bill the Lab Guy's teenage daughter.
- A Day in the Limelight: "The Quarky Syndrome" is an episode that focuses primarily on her.
- Damsel in Distress: In "Big Baby", Big Baby captures her and the Action League must calm him down to rescue her.
- Puberty Superpower: In "The Quarky Syndrome", she gets hit with nuclear waste from The Mayor's nuclear reactor and becomes a superhero named Superteen, gaining the abilities to fly and shoot lasers from her eyes.
- Put on a Bus: She stopped appearing on the show after the second season.
- The Smurfette Principle: She's the only other main female character besides Thundergirl.
- Unwillingly Girly Tomboy: She wants to be a scientist, just like her father. However, it is revealed in "The Revenge of Hodge Podge" that Bill makes her take up ballet, which she hates.
- Evil-Detecting Dog: In "Hey, Who Stole My Face?", he is the first one to notice The Mayor impersonating The Chief by wearing his face, as he growls angrily at The Mayor and bites him.
- Team Pet: The league's faithful dog.
- Timmy in a Well: He often warns The Chief whenever The Mayor is up to something evil.
The main antagonist of the show.
- Archnemesis: To The Action League and he is the most recurring antagonist.
- Big Bad: The most frequent villain in the show.
- Catchphrase: "Uh oh, here's trouble." whenever something goes wrong.
- Corrupt Politician: He's the mayor and a villain.
- Evil Sounds Raspy: He speaks in a hushed and hoarse voice.
- Faux Affably Evil: When interacting with the heroes, he always addresses them with mock politeness.
- HeelFace Mole: In "Turkey Of Terror", The Mayor invites the Action League to his mansion to form a truce with them. Stinky Diver doesn't go because he believes this to be a trap, and he later turns out to be right.
- Laughably Evil: Given what kind of show this is, it's not surprising.
- Mayor Pain: Of both the "Evil" and "Incompetent" varieties.
- No Celebrities Were Harmed: He is given the same voice that the WDVE crew gave to then-mayor of Pittsburgh, Tom Murphy.
- Punch-Clock Villain: In "The Wrath of Spotzilla", he was enjoying a soccer game when Spotzilla attacked. He panicked with the rest of the crowd.
A baby doll who makes havoc on its way until tamed.
- Attack of the 50-Foot Whatever: He is two-feet tall, which is tall compared with other toys.
- Creepy Doll: He cries in a creepy tone and leaves devastation in his way when not satisfied.
- Hulk Speak: He speaks in third person with an adult male voice, as in "BABY MAD!"
- Sealed Evil in a Can: Big Baby was in a toybox in the basement until the KISS concert accidentally woke him up in the episode Rock-a-Big-Baby.
- Anti-Villain: The reason why he wants to destroy the League and Bill is because despite it being an accident, they ruined his life.
- Create Your Own Villain: Was the Action League's accountant, but became the freak he is now thanks to the incompetence of the Flesh & Bill the Lab Guy.
- From Nobody to Nightmare: He went from being the Action League accountant to a mutant cyborg thanks to an accident involving a blender and being put back together with Bill's various spare parts.