The phrase "last man" can be said in many ways depending on your intended meaning. "Survivor," for example, is a word that refers to the last person remaining in a group or situation. If you're talking about someone who's the ultimate authority, "supreme ruler" or "dictator" might be better ways to describe the last man standing. Similarly, "champion" or "victor" could refer to someone who finished first in a competition, beating everyone else. On the other hand, "last in line" or "trailing behind" might be used to describe someone who is physically at the end of a group. Ultimately, the synonym you choose for "last man" depends on the context of your sentence.