Doomguy. The lone saviour of the human race, protecting us from the evil demons of Mars. From
Doom.
Duke Nukem. The lone saviour of the human race, taking down the lady stealing pigs of space. He's looking a lot like Bruce Willis lately.
Gordon Freeman. The lone saviour of the human race, freeing us from the tyranny of interdimensional brain bugs. From
Half-Life.
Solid Snake. Probably isn't the lone saviour of humanity, but he's still fighting the good fight in the eternal struggle against Metal Gears, clones, and a crazy old bastard with a cowboy obsession.