Or maybe Enrique Iglesias. I can be your hero baby...
Sorry.
I think a hero is someone who performs a heroic act. I also think it's undefinable past that, because heroic acts can take on (in my opinion) so many different forms, and involve so many variables. One aspect of heroism that I think is intrinsic in all acts though, is a glorification of them, and I think there are acts that can be morally greater than heroic ones, yet their lack of glorification disqualifies them from being heroic. I consider firefighters to be heroes, yet despite the goodness in their acts, I think Mother Teresa has done more good than any firefighter I could name, yet she was not heroic. She did not fit a glorified archetype, and her actions, while incredible and awesome in their compassion, did not have, to my mind the sort of glorified, idol worship-inducing, type of qualities. I applaud anyone who can understand what I'm trying to get at, as it's very difficult for me to even explain this to myself, much less other people.