Here’s an “if-you-can-find-it” one:
Flamma Flamma from the Fire Requiem by Nicholas Lens.
I used to play the video when I was a VJ 6 or 7 years ago. It was mostly voice driven but the tension that was built into it was AMAZING.
Mussorgsky: Night On Bald Mountain
Or his Great Gates of Kiev That was a cool one, too. Great for an entrance.
Also, someone mentioned the Conan The Barbarian soundtrack before. I don’t know if you’re allowed to use soundtracks, but is without a doubt one of the greatest symphonic movie soundtracks ever. Just make sure you don’t get Conan the the Destroyer by mistake. It wasn’t as good.
Many excellent suggestions so far. A few more:
Finlandia by Sibelius. (Used in Die Hard 2 to great effect)
In the Hall of the Mountain King by Grieg
Shostakovitch’s Symphony #5, beginning of the 4th movement
In addition to the Dies Irae, the Confutates from Mozart’s requiem is excellent. A little less bangy, a little more moody.
Mahler has lots of great stirring stuff, although I can’t think of a movement that has a snippet right from the beginning that would make it easy to use. Certainly, the climactic parts of Symphony #1 or Symphony #2 would both work great.
If you want your character to come off as hilariously egotistical, you could throw in The Hallelujah Chorus. (Actually, parts of it would work pretty well in any case… “King of Kings” (forever, and ever) “And Lord of Lords” (Hallelujah, Hallelujah) (and so forth))
Another somewhat humorous choice would be Tchaikovsky’s 1812 Overture. You could beat your chest in time with the cannons, or something.
Even badder bad-ass Wagner would be Siegfried’s Funeral March If it was good enough to be Arthur’s theme music in Excalibur, it’s good enough for you. 
I thought of two pieces of music…
Montagues and Capulets by Prokofiev, which a couple people have already mentioned.
AND
Entry of the Gladiators by Julius Fucik. Definitely check this one out. 
The Firebird Suite by Stravinsky appears to have been overlooked, so far. And there are probably some good bits from Rite of Spring, too.
There’s probably a fair bit of instrumental soundtrack music that would fit the bill, but I don’t know if that would fail for being “totally modern”. Hans Zimmer has written some good stuff for the likes of Crimson Tide and other movies. Matt Uelmen also has some stuff written for Blizzard, the video game company, that would probably fit. The Batman and Terminator movies also had music that might work… but might fail for being too recognizable. What exactly is “too modern”?
Lotsa good suggestions so far.
Liszt’s Les Preludes.
The very end of Debussy’s La Mer. There are other spots as well.
From Ravel’s Daphnis and Chloe, the “Danse guerriere” (“warrior dance”) and its lead-in. It’s included at the end of the suite #1 from the ballet. Also the “Danse general” at the very end of the ballet (included in suite #2).
The middle of Debussy’s nocturne for orchestra, Fetes. The section I have in mind starts with soft brass (in the distance), then crescendos from there.
There have been some great suggestions here. I would suggest that when making your choice, you consider the text and context of the music. Requiems are works of mourning for the dead. based on Biblical texts. Although the “Dies Irae” from the Verdi “Requiem”, among others, has been abused for commercial purposes, it is still a piece that has meaning for many people. For me, it is associated with the deaths of 9/11. Likewise, use of the “Hallelujah Chorus” for your purposes might be offensive to some.
Please let us know what you choose (or we may be forced to come after you with an 18"DHIBJD :eek: :eek: ).
From the album Schauspeluden
Goddesses, 2:51
Michaeleska, 2:12
Of course if you were Edward Beerslayer, a nice drinking song Tummel Dich, gutes weinlein =)
Go for period music=)
samples of the first 2 are on the site…
Of course there is a nice processional from their album Danza=)
Throwing in another Wagner/Ring cycle selection: Magic Fire Music. It’s both menacing and heroic without all the pop culture baggage so many (but not all) of the other selections listed above have. This version (play Track 3) omits the singing if you prefer the symphonic version for maximum effect.
The Firebird is one of my absolute favorite pieces, but the most obviously ass-kicking part has much more of a “A ha, triumph has been achieved” feel than a “I’m here to kick ass and chew gum, and I’m all out of gum” feel, imho
Plus it’s in 7
Of course there the mad king’s mad dance… but that would be, well, mad
Could it be written “recently,” but still classical sounding? If it does, I might suggest…
•Inquisition Symphony, by “Apocalyptica,” a Metalica-tribute band of…cellists.
•Or maybe [the=http://www.amazon.com/exec/obidos/ASIN/B00006GOHM/qid%3D1090040965/sr%3D11-1/ref%3Dsr%5F11%5F1/102-5555246-9613700]The String Quartet Tribute to Black Sabbath, if you really want “Iron Man.”
•Or the obvious, Dead Can Dance’s Aion. I’d reccomend “Saltarello” from the latter—which, as it happens, is based from a 14th Century Italian dance.
•That, or maybe something peppy by the Medieval Baebes, like Kinderley or Gaudete. If you have any “Amazons” fighting, they might like it.
•Or Jupiter from Holst’s The Planets. Hail to the king, baby.
In any case, be sure to report back with us on how things went at the fight. Pictures too, if you can manage.
Here’s a suggestion from left field:
I’d check out the soundtrack from Princess Mononoke. More specifically, I’d find a copy of the Princess Mononoke: Symphonic Suite CD, and check out track 7, “The World of the Dead - Adagio of Life and Death.” Lots of different spots that you could grab 20 seconds of.
“The Hall of the Moumtain King” from **Pier Gynt ** (Grieg)
Berlioz, “Tuba mirum” from Grande Messe des Morts. I’m not too familiar with this piece, and other parts may be useful.
Also parts of Berlioz’ Symphonie Fantastique, especially “March to the Scaffold”.
The fourth movement of Shostakovich’s Symphony No. 5 in D Minor. It starts out with a bang right away and it’s got a great tune.
One of the Bad-Assiest pieces ever, IMO 
.
Oy, dammit, didn’t see that MaxTheVool already mentioned Symphony No. 5 :smack: .
Another suggestion: Try this one piece from Prokofiev’s The Love for Three Oranges Symphonic Suite. IIRC, it’s called “Magician Celio and Fata Morgana Play Cards.”
I might suggest Amilcare Ponchielli’s Dance of the Hours…
Wow, this event sounds incredibly, embarassingly geeky. Just the way I like my entertainment :D. Where is this taking place at?