I Am Legend.

In Will Smith's last release I Am Legend, Will Smith plays a lone survivor (Robert Neville) of a deadly virus caused from the vaccine for the cure of cancer. His quest is to find the cure for this virus by any means necessary and in the end he ends up sacrificing himself to save the vaccine from the mutants.
Later in his quest Robert meets two new characters. Anna (played by Alice Braga) and her son Ethan (Charlie Tahan). These characters urge Robert to join them on the trip to the colony of survivors but he refuses, saying that he must find the cure and needs the infected to do so. At the end the infected people find his home and them, chasing them into his laboratory to find the cure worked on the infected, bringing her back to life. Robert hands the cure to Anna telling her and Ethan to hide in the small enclave while he distracted the mutants, thus leading to his demise.

Robert Neville personifies the definition of hero, one who sacrifices themselves for the good of others. This movie really seemed to affect me and made me think of how one man can save millions of others.