Now that you mention it, other variations on the lone-hero theme I often find interesting -- e.g., Raymond Chandler's Philip Marlowe, one of my all-time favorite characters. Chandler gave a lot of thought to the idea of the private investigator as knight errant -- e.g., from Chandler's essay "The Simple Art of Murder":
"... down these mean streets a man must go who is not himself mean, who is neither tarnished nor afraid. The detective in this kind of story must be such a man. He is the hero, he is everything. He must be a complete man and a common man and yet an unusual man. He must be, to use a rather weathered phrase, a man of honor, by instinct, by inevitability, without thought of it, and certainly without saying it. He must be the best man in his world and a good enough man for any world. I do not care much about his private life; he is neither a eunuch nor a satyr; I think he might seduce a duchess and I am quite sure he would not spoil a virgin; if he is a man of honour in one thing, he is that in all things. He is a relatively poor man, or he would not be a detective at all. He is a common man or he could not go among common people. He has a sense of character, or he would not do his job. He will take no man's money dishonestly and no man's insolence.... He is a lonely man and his pride is that you will treat him as a proud man or be very sorry you ever saw him."
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Carl