The God-Emperor of Mankind (Warhammer 40.000) is badassery incarnate.
Nagi Springfield (Mahou Negima Sensei), the legendary "invincible" Thousand Master.
Erased from existence? Returns to life through sheer willpower.
Reality Warping? Just dodge!
Trapped in another dimension? Break it through muscle-flexing.
Facing God? Shoryuuuken!!!
The solution to everything.
Name's Kratos. Born a demigod, took down all of Greece's mythical monsters and its entire godly pantheon. Any questions?
Asura's badassery in a single picture. Guess what? He won. Then he proceeded to best & bury a slew of tyrannical super gods along with their cosmos spanning celestial armies, took down a planetary ungodly abomination which could shatter stars & planets and finally, subsequently, killed the unstoppable Demiurge who created it all... bare-handed.
Duke Nukem kicks alien ass and looks good doing it.
Charles Nelson Reilly (CNR) is 8 feet tall, won the Tour de France With two flat tires and a missing chain and ran a four-minute mile blindfolded With an engine block strapped to his back among other impossible feats.
Charles Nelson Reilly (CNR) has Chuck Norris' head mounted on his wall.
Kenshiro (Fist of the North Star) marked an entire generation of readers as one of the founders of the concept of badassery.
Saitama (OnePunch Man); because doing an every-day training routine allows you to punch a hole through a freaking planet!
Kenshin Himura (Rorouni Kenshin/Samurai X), The Battōsai.
Hiei (YuYu Hakusho)
Guts (Berserk), The Black Swordsman.
Killua Zoldyck (Hunter X Hunter) The Zoldyck Family's prodigy assassin who was already an expert at a very young age!
Yusuke Urameshi (YuYu Hakusho) This guy stands out from every other Shōnen protagonist!
Mary Sue (Ensign Sue must die!) Has the unnatural ability to seemingly never fail at anything despite doing not much but annoy people.
Saxton Hale (Team Fortress2 Comics) achieved countless impossible and or just plain badass feats in his life including -Fighting off a lion while simultaneously having a haircut. -Single-handedly wiping out the Indonesian Berserker Shark (and making them cry). -Eating a whole ostrich. -'Manslaughtering' 1593 physicians. -Inventing the "high-five". and many more
Zetta (Nippon Ichiverse) the "Most Badass Freakin' Overlord In The Entire Universe".
The Doom Marine (Doom Slayer/Doomguy) is a warrior whom has slayed most of Hell's Legions and saved the Earth from being destroyed by the Demons. He has an arsenal of powerful and destructive weapons, a suit of enchanted power armor, and the legendary BFG. But his greatest weapons are his fists.
Alucard (Hellsing) is regarded as the most bad-ass vampire in existence.
Kenpachi Zaraki (Bleach) is so badass, he can defeat a Reality Warper by sheer badassery. How? Because the Reality Warper tried to make himself more badass than Zaraki, and found out this was literally impossible.