A request by
Honorable mention on this list for mercenary Samus Aran before Other M completely (and unfortunately probably canonically) destroyed her.
Also the ultimate badass Max Payne because I'd probably put him on top of the list but I restrained myself and went with something less predictable...
10: Agent 47
From : The Hitman Series
Agent 47 is a graceful, remorseless device of stealthy execution. Even when a player mucks up playing him he can still make an ill-advised firefight to the death look stylish. 47 is cool under pressure, iconic, and makes assassination look so effortless it's scary.
9: Adam Jensen
From : Deus Ex : Human Revolution
It seems like stacking the deck that most of Jensen's awesomeness comes from artificial augmentations, but even before that he was a cop who literally didn't play by the rules and in the tutorial level kicks all kinds of terrorist ass without a single implant. He also has one of the gruffest and impartial voices in video games.
8: Master Chief
From : The Halo Series
Abducted as a child and forced to endure the most grueling physical training to become a colonial enforcer, Master Chief is notable for being augmented genetically so in addition to his near impervious armor AND shield he's superhumanly strong and fast. Regardless he keeps winding up in situations nearly over his head, but manages to muddle through with the same perpetual, professional calm.
7: Matthew Kane
From : Quake IV
Matthew was a war hero even before arriving on Stroggos and he manages to serve with distinction...until he's captured and nearly turned into a mindless cyborg drone. At the last moment he escapes, his body and mind irrevocably altered, but now all the more an asset to humanity with a unique understanding of the enemy he faces. He's been somewhat forgotten but has the distinction of being the only major character I can think of who in the course of the game loses ALL of his limbs without anesthetic, and recovers enough to fight another day.
From: Heavenly Sword
I haven't played this game, but I HAVE seen the official movie, and Norkio is a badass. All her life she's lived in the shadow of a prophesy: declared a failure and a curse for not being born a man. Interestingly she resents this but does not go out of her way to retaliate: staying firm in her conviction to protect her clan even without recognition. The sword she carries although magical is only as good as the one carrying it, and she can unlock all kinds of crazy abilities with it (including duel chain blades developed at the same time as another God of War tried the same thing.) Selfless and a little snarky Norko can take on an entire army without breaking a sweat.
5: Canderous Ordo
From : Star Wars : Knights of the Old Republic
Not only does this Mandalorian mercenary wield a laser chain gun which he hefts like it's made of paper his war stories the player can hear involve such notable actions as riding on the back of a Basilisk warlord through the atmosphere into battle dodging beam weapons without wearing armor. A clone trooper during the clone wars who showed distinction was called 'Ordo' in his honor hundreds of years later. THAT'S a badass.
4: Garrus Vakarian
From : The Mass Effect Series
He's Batman if Batman was an alien with a sniper rifle. When he isn't serving in official capacity as one of Commander Shepherd's commandos he's pot-shorting smugglers and gangsters in retirement because it gives him something to do. He's got a conscience under the hood but he's not afraid to fight if it comes down to it. He's fiercely loyal, looks even more intimidating after getting the business end of a chain gun AND a rocket launcher, and is probably one of the most memorable faces of the entire franchise apart from Shepherd himself.
3: The Doom Marine
This is probably nostalgia on my part, but I always considered this guy close to the coolest dude ever. His back story details how he disobeyed orders to save civilians from a high command botch and so was exiled to Mars as a security officer in punishment. When all Hell literally breaks loose he goes to war with the combined forces of a demonic dimension using CONVENTIONAL WEAPONS. Until the BFG comes into play the Doom Marine is literally battling devils using a shotgun, a pistol, and a chainsaw! Chalk it up to bad resources but this ordinary guy has the potential to survive an entire station worth of monsters using hot lead.
From: Mortal Kombat Series
Nightwolf really came into his own as an excellent character in Mortal Kombat Nine. Instead of a carbon-copy 'young warrior' or a painfully stereotypical native token, Nightwolf is portrayed as a real Native American shaman who is noble, heroic, and very even in his attitude despite the situation. He's extremely powerful and doesn't need armor or weapons: just his shamanistic faith. He goes toe-to-toe with gods and monsters and until much later he always comes out on top. I was immediately impressed by his statement to Scorpion 'I understand the pain of my people being oppressed...but I have learned to heal instead of hate.' A Native American character who is about something other than anger at white people? Still unprecedented, and it allowed Nightwolf to actually be a CHARACTER instead of a stereotype. Fans, myself included, are still waiting for him to come back already...
From: The Legend of Zelda Series
He's not only a badass once, EVERY person from his bloodline at some point in history has been one. He fights sorcerers and monsters that tower above him with a sword and a wooden shield. He doesn't need to quip or really talk at all so he subsequently never asks why he must risk his life for others: he just does it. Resourceful, surprisingly strong, agile, and courageous to a fault Link has been through any number of trials in any number of incarnations but managed to preserve through sheer stubborn resolve.
He might dress like a Peter Pan cosplayer, but he is still the king of badasses in my opinion.