- last post: 01.01.0001 12:00 AM PDT
They never give a last name, even in the books. They leave it like this for the same reason they never show his face. Other than the fact that he's male, he could be anyone, a last name would denote a nationality or some other trait, it would make him too concrete. As he is now, when you're playing through as Master Chief YOU are in that helmet.
Granted, the books do describe his face in small detail, but mainly that it's extremely pale from never being in sunlight, as are all spartans. Anyways, my two cents.