Super Mario RPG
I fudged things a little bit, and rated this track a little more highly than I might on its own for history's sake. Bowser is the end boss. He originated the concept and has carried the mantle more than probably any other villain in video game annals. And in nearly every appearance, Bowser's battle music kicks ass. (It's too bad Bowser never does, but still!)
I chose this music to represent Bowser, edging out the Super Mario 64 iteration, because (a) this is the best music of the group, and (b) Bowser peaked in Super Mario RPG. Most Valuable Character in that game, if you want my opinion. And if you disagree, please, allow me to retort.
Like the moon over
the day, my genius and brawn
are lost on these fools.