The old English word for this was forthirst. It was a direct counterpart to the modern "starve." But it fell out of use because it happened so rarely in the British isles. I don't know Arabic but I'm willing to bet they have a word for it..
Doing what you believe to be right despite severe personal consequences.
The subjective part is that what you think is right and what others think is right differs. You're only a hero if most people agree that you did the right thing I guess.
You probably need to be decently upstanding, too. Some might say the child rapist in your example committed a heroic deed by dying fighting a wildfire but people would not call them a hero.
I think sometimes people can be heroes without extreme sacrifice, too. For instance, I would call Fred Rogers a hero solely because of his positive impact on others.