Final Fantasy V
Today this track is more commonly known as Battle With Gilgamesh or something similar, and may even be listed on some soundtracks as such. But originally it was called Clash On The Big Bridge, so that's what I'm sticking with.
In case you've never played a Square game in your life, let me explain: Gilgamesh is the greatest Ensemble Darkhorse in the history of gaming. He was kind of the vice president of Team Evil, Exdeath's right hand man, in Final Fantasy V, an extremely fun game most Americans didn't play until after they'd been through VII or even VIII for the very simple reason that it wasn't released in the U.S. until after those games. (Hence why Final Fantasy VI was called Final Fantasy III in the U.S.) FFV was a transition game between the interesting but fairly boilerplate plot and gameplay of FFIV and the very deep and polished FFVI that forever raised the bar for RPGs. Some story elements were lacking--just to pick an obvious example, the big bridge was called "The Big Bridge"--but the gameplay was very fun, and the job system now well known from later games was invented by FFV.
Back to Gilgamesh. He was a surprisingly affable guy for a servant of Exdeath, not that it's ever explained why he's defending an eldritch abomination like Exdeath in the first place. The guy never shuts up. It's not like he's constantly taunting you or anything; he just likes to make casual conversation while he's trying to kill you. Truly Gilgamesh takes the concept of "hey, it's nothing personal, just doing my job, you know?" to higher levels. Then in the Very Definitely Final Dungeon he performs the most predictable Heel-Face Turn in history, and then blows himself up. The end.
Gilgamesh was the most popular villain ever until Sephiroth came along, and it's become traditional nowadays to include a Gilgamesh battle in every Final Fantasy game, somewhere. The question has been posed, why is Gilgamesh so ridiculously popular? Well, it's true: he's cool, and funny. But someone, somewhere said something I never forgot:
It's the music.
And he was right. It's the music.