Final Fantasy VI
This is not music you can assign to just any punk boss. It's not even music you can assign to just any non-punk boss. This is music that makes it clear right from the first note that you are in some serious shit. It's assigned to only one boss in all of Final Fantasy VI before the Very Definitely Final Dungeon: Atma Weapon. There's no build-up to the fight with Atma Weapon except a few rumors you heard around town about "a monster bred for mass destruction" and the fact that you're on the Floating damn Continent while Gestahl and Kefka are screwing around with the damn Statues. So you figure you're in for something rough when you get up to the top of that thing.
And boy, are you ever. Atma Weapon is no girly monster. Why exactly Atma Weapon wants to prevent you from interfering with Gestahl seems like a mystery, but it does make sense: he's all about mass destruction after all. Since Kefka (if not Gestahl) is there for the express purpose of wrecking the hell out of the world, it stands to reason that puts him and Atma Weapon on the same team, more or less. Ergo, Atma Weapon lets Team Evil right on by but is not about to let Team Good crash the party.
Then this music plays, and you think: oh shit. And with good reason.
You won't hear it again until you happen upon Atma Weapon's big brother, imaginatively called Atma, who is sitting around minding his own business in a random prison cell in the Very Definitely Final Dungeon. By then, of course, unless you're doing a low level game, you will confront him with a party full of gods and wipe the prison walls with his organs. But still.
And then, of course, the Goddesses themselves get this heart-pumping music. They're just the hors d'oeuvres before you throw down with Kefka. (You won't see THAT music on this list for a while yet.)