Since I have blogged before about the degree of obligation that I think teachers have to their students, I feel like I can't refrain from mentioning Liviu Librescu, an instructor at Virginia Tech who sacrificed himself by bodily blocking the door so that his students could all escape out the window. This is of course above and beyond the call of duty, but well within the realm of heroism. Eugene Volokh has more.

Porthos felt the very earth beneath his feet becoming jelly--tremulous. He stretched both hands to repulse the falling rocks. A gigantic block was held back by each of his extended arms. He bent his head, and a third granite mass sank between his shoulders. For an instant the power of Porthos seemed about to fail him, but this new Hercules united all his force, and the two walls of the prison in which he was buried fell back slowly and gave him place. For an instant he appeared, in this frame of granite, like the angel of chaos, but in pushing back the lateral rocks, he lost his point of support, for the monolith which weighed upon his shoulders, and the boulder, pressing upon him with all its weight, brought the giant down upon his knees. The lateral rocks, for an instant pushed back, drew together again, and added their weight to the ponderous mass which would have been sufficient to crush ten men. The hero fell without a groan-- he fell while answering Aramis with words of encouragement and hope, for, thanks to the powerful arch of his hands, for an instant he believed that, like Enceladus, he would succeed in shaking off the triple load. But by degrees Aramis beheld the block sink; the hands, strung for an instant, the arms stiffened for a last effort, gave way, the extended shoulders sank, wounded and torn, and the rocks continued to gradually collapse.
"Pothos! Porthos!" cried Aramis, tearing his hair.

Alexander Dumas, The Man in the Iron Mask