Modern heroes are a lot like ancient heroes, but with some major differences. To begin, the flaws of the hero are much more prevalent in modern times. The flaws of a modern hero are much more intense than in ancient heroes. This is because modern humans want someone they can relate to. Also, most modern heroes take the form of either the underdog, or the unwilling hero. This is because modern people want to hear rags-to-riches stories, mostly because they wish to be instantly successful themselves.
Overall, the modern hero is more "human". Ancient heroes epitomize the socially acceptable aspects of the time and place. Modern heroes usually show an imbalance of negative aspects to positive ones, but always succeeds in the end. Where ancient people wanted someone to model themselves after, modern people want someone to relate to.