I'm just a man who's good at what he does, killing. There's no winning or losing for a mercenary. I've never fought for anyone but myself, I've got no purpose in life, no ultimate goal. It's only when I'm cheating death on the battlefield, the only time I feel truly alive.
~ Solid Snake

Byronic Heroes are charismatic characters with strong passions and beliefs, but who are nonetheless deeply flawed individuals who may act in ways which are socially reprehensible because they're definitely contrary to their mainstream society.

Byronic heroes (who are sympathetic) disagree with society and say "Screw the rules, I'm doing what's right!" despite the heavy price that this costs them. A byronic hero is on their own side, and has their own philosophy which they will not change for anyone. Their internal conflicts are heavily romanticized. They can be very cerebral characters. These heroes also ponder and wrestle with their struggles and beliefs.

These are sometimes a sub-category of Chaotic Good and are occasionally the opposite of Lawful Good depending on the character.

Those heroes are rarely pure good or even outright due to their nature, and usually belong to the Grey Zone.