I think that what makes a character or real-life person a hero for me is courage, a strong sense of what is right or the best thing to do and willingness to adjust their moral code and take moderate risks when it is needed, not because they were too stupid to overlook something that could've make that risk unnecessary.
For example, a motorcyclist with a malfunctioning brake making the bike go over the speed limit "sacrificing" himself because he only took along one helmet is not a hero because the risk was unnecessary- he could easily have taken another helmet so that his girlfriend wouldn't have to wear his. (Add a smiley to your reply if you know what I mean- reference for those who know the story I'm talking about, posted on message boards, or sent by friends).
-Morwen
