Vilgax from Ben 10 when Ben was still 10. Admit it. Easily the most Badass person on the show. Ben couldn't take him in a fair fight but HAD to win on a TECHNICALITY. He unfortunately went through Badass Decay in Alien Force.
Both the eponymousAeon Flux and Trevor Goodchild. Unlike most of the examples of this list, Aeon is particularly known to constantly subvert her own badassery by making incredibly stupid mistakes.
Brock Sampson from The Venture Brothers is the epitome of brutality and machismo. Over the course of the show, he is seen maintaining a vicious death-grip on a man while being shot with at least 20 tranquilizer darts and run over by a van, killing two men with his rectum, and tearing out a man's eyeballs and making him dance like a marionette with his optic nerves (these are only a few instances).
All while protecting charges that he'd rather throw off a cliff.
Brock Samson: Now, Hank, touch your throat. That tube you feel is your trachea. Think of it as your handle. That thing your thumb is on is your carotid artery. Think of it as your button. I want you to grab the handle, push the button. Can you repeat that, Hank?
Hank Venture: [gasping] Grab the handle, push the button.
Brock Samson: Let go of your own throat, Hank.
Since Brock Samson is in this list, why not mention the original? That's right: Roger "Race" BADASS Bannon, of Jonny Quest fame.
The main character from Korgoth of Barbaria, Korgoth, is an almost stereotypical example of a badass.
Cartman from South Park as The Coon, in "Coon & Friends". And as The Dawg in "Miss Teacher Bangs a Boy".
Anyone from Beast Wars at some point, including Dinobot and Depth Charge constantly. Every character gets a chance to shine, usually by beating characters from the other side into springs and slag. Hey, war's in the title.
The Dinobots from G1, especially in the comics. They're vicious, savage, completely out of control, and on the side of the good guys.
G1 Mirage, at least in the cartoon, was incredibly badass. He pulled daring stunts, and was a match for most of the Decepticons be it in gun battles or hand-to-hand combat. He could even give Megatron a run for his money. Mirage didn't want to take part in a war... so he's going to make the Decepticons pay for not leaving him any choice in the matter.
Megatron in Animated can beat all of the Autobots single-handedly and is one of the few version of the character to actually punishStarscream for his betrayal.
At one point in the series, he gets contained in a force field with an Omega Supreme clone, set to self-destruct at a power sufficient to destroy everything in a hundred-mile-radius. He survives.
In the same vein, Animated Optimus Prime is pretty badass too. He fights this Megatron solo, which takes ball bearings in itself, and once entered an Autobot ship that had been captured and rescued all four captured Elite Guard bots, beating five Decepticons, all of which were combat-ready and willing. He also spends his free time being one of Detroit's superheroes and the leader of the other four heroes.
Optimus Prime, no matter what the incarnation, is the one true badass of Transformers. He's a pacifist and tries to solve things non-violently, but when you mess with peace, you can expect to lose a face...
As well, Optimus Primal—who, while being the analogue for Optimus Prime for Beast Wars was a unique Transformers leader the likes of which wouldn't be seen until Animated. He was once quoted as saying "Sometimes crazy works," which, while not his Catch Phrase, was his modus operendi.
We have Korra, the cocky, perky hero who can take on anyone and anything and started bending three elements at four years old
Aang's son Tenzin, the mentor figure and the last Airbending master on the planet, who lives with his family on a private island
Chief Beifong, Toph's daughter and head of Republic City's metalbending police force and has been essentially stealing the show in every combat scene she appears in.
And lest we forget her finest moment, in a moment of complete selflessness, she launches herself at two airships pursuing Tenzin and his family and tears one of them apart by herself. After being captured, she all but spits in Amon's face when he offers to let her keep her bending in exchange for Korra's location and unlike everyone of Amon's other victims so far, calmly accepts her fate.
Mako and Bolin are major badasses as well - professional athletes that compete in battles against other benders. Just moments after we meet him, Mako finds himself alone against three opponents in a probending match, takes the third round in an impressive show of skill, and wins it by himself when he knocks all three of his opponents into the water, by tiring them out while he dodged everything they threw at him, while teetering on the arena's edge.
And Katara is still alive, appears to have been Korra's waterbending teacher, and may possibly be a Grand Master of the Order of the White Lotus. She's the only member of the Gaang left alive, at 84 years old, and somehow found time to give birth to three kids.
Before taking anyone's bending away, Amon has always allowed his victim to fight for their bending. Not a single bender has even put up a fight against him so far. He even resists bloodbending from Tarrlok, arguably one of the most powerful waterbenders in the world and defeats him with ease.
Tai Lung. Nowhere is that truer than when he escapes his prison: 1000 guards, giant crossbows, a holding cell a mile underground and personal restraints specifically designed to neutralize his kung fu abilities; the warders didn't have a chance. This becomes even more evident when you learn, as revealed in the Art of Kung Fu Panda, that a) the prison was built specifically for him, and him alone (after the creators decided this would build him up into even more of a threat) and b) he learned his signature nerve-paralyzation move from the very restraints holding him prisoner.
A certain "crazy old turtle" who defeats Tai Lung with a few hand gestures.
Furious Five in that battle on the "Thread of Hope". That was BADASS!
Anyone not expecting moment upon momment of Badassery in Justice League Unlimited with the opening scene of Green Arrow beating up robbers and talking smack to Green Lantern (homage to the Green Lantern Green Arrow comics?) they only had to wait 5 minutes for the revamped, Rock Opera theme song, which disabused that notion in spades.
Hawkgirl ("Less Talking, More Hitting") and her Big Honking Mace.
"Ask yourselves. Is being in here with me what you truly desire?" J'onn J'onzz reminds Task Force X why he is the sole surviving Martian.
Batman continuously attacks DARKSEID, despite knowing how useless it was given that he was a mere mortal hitting a Physical God. He kept at it and dodged Darkseid's one-hit-kill, homing Omega Beams. Even Darkseid was impressed by this.
All the main characters of Teen Titans fit this trope at one point or another, but the creators paid special attention to making Robin as Bad Ass as possible, to the point where he hits the bad guys just as hard as his superpowered comrades.
And Slade trounces them all in Badassitude. How badass is he? He's voiced by Ron Perlman; he's that badass.
Coop from Megas XLR simultaneously subverts AND supports every fat character trope there is, while throwing a fair bit of audacity and affection into the mix. Coop is loving Deconstruction of the hot-blooded Super Robot pilot. A deconstruction because he regularly fights and promptly destroys many thinly disguised icons in anime, and pop culture in general...but the very fact he's a fat guy and the protagonist is unusual in itself. Loving because he also embodies everything that makes hot-blooded, screaming heroism so awesome. And it's that quirky mix of his purpose, his appearance, and his personality that make him badass.
ThunderCats (2011) has Panthro, who, according to Michael Jelenic, is "a pretty cool character, just like on the old show." He repeatedly mows through multiple foes with ease, whether in his personal tank, or toe-to-toe against a group of lizards while armed with only one nunchaku.
Just about everyone in Motorcity. Especially Mike Chilton.
Sterling Archer has proven to be Badass many times, especially in the two parter when he had gotten cancer, and his friend who also had cancer died from fake medication. In which Archer went on a rampage infiltrating the illegal drug ring and killing every single guy he saw, even to the point where he was so sick he could barely walk he was still killing guys left and right. He then gets to the Big Bad of the episode who was a feeble old man who stated Archer would never kill him, his conscience wouldn't allow it. (He was dead wrong)
His partner Lana is equally as badass.
Quest from World of Quest fits this perfectly.
Several characters in Sym-Bionic Titan. Most notably Solomon, followed by Lance, although Ilana and Octus are this at points as well. General Steel is arguably this at one point or another.
Rainbow Dash from My Little Pony: Friendship Is Magic is the biggest one of the mane six by far. She kicked a fully-grown dragon in the face and made it flinch and she's the only pony ever to break the sound barrier.