I’ve never read any of the books, but I’m not sure Flashman counts as a hero. (Maybe a “hero”?)
For that matter, my suggestion of Macbeth is probably inappropriate. Even though he starts out as a highly praised war hero, it sure doesn’t take him long to turn to villainy.
I still maintain that Othello, although a jerk, is an archetypal flawed hero.
Now that’s really interesting.
Othello is a decisive man of action. Hamlet scrutinizes and overthinks everything around him.
In each other’s shoes they probably would have foiled their opponents in short order, but in their own stories, their traits are fatal flaws.