After watching the movie Manhunter last night on TV I have to go with Ina Gada Davida (sp?). Watch the end of the movie and see if you don’t agree
Cossack Patrol, by Ivan Rebroff (I think it’s an old Russian folk song, or something.) As seen here on rathergood.com
Oh!, Enough by Gravity Kills would be perfect as you personally engage in wanton destruction and unleash your terrifiying powers on an unprepared world.
My speed always jumps by about 15mph when I hear this in the car.
I remember the theme to The Andy Griffith Show being whistled menacingly in a short lived TV show a while back. Sent shivers EVERYWHERE. Think it was called American Gothic. Not sure though.
That would be Iron Butterfly’s In-A-Gadda-Da-Vida, the first classic heavy metal song (1968).
The Beatles’ “Run For Your Life” is an ideal psycho-stalker theme song.
The Rolling Stones: “Sympathy for the Devil”
The Doors: “The End”
The soundtrack from The Final Conflict (the third Omen movie) is wonderfully menacing and megalomaniacal, particularly the main title and the fox hunt sequence. The soundtrack for Hellbound: Hellraiser II has similar charms. Both are far better than their respective movies.
As for pop tracks –
Public Image Limited’s The Order of Death
The Smashing Pumpkins’ Zero
Radiohead’s Everything in its Right Place I think would make a great soundtrack to a killing montage where the evildoers sneak into people’s bedrooms at night with knives.
The 5th mov’t to Berlioz’s fantastic Symphony is a very evil narrative. An artist, thoroughly rejected by his ultimate female object of desire in earlier movt’s, now in an opium-induced nightmare imagines himself dead and and looking on to a party that this woman is having. She is now a witch and seems to be celebrating his demise with all the other evil spirits. Oh, and it desearves mention for using the Dies Irae theme.
Excerpts from Bartok’s Bluebeard’s Castle.
Ozzy Osbourne’s Diary of a Madman.
Steve Reich’s Proverb I think would be interesting behind a sorta satanic ritual sacrifice-type thing.
The theme from “Phantom of the Opera” is now stuck in my head.
Evil genius/madman incarnate 
… And I’ve now got to track down the Techno Remix of it I heard years ago.
Movies usually cement the scene, although I’m trying to come up with something original… and failing, so
Pink Floyd - The Wall : In the Flesh/Run Like Hell
David Bowie/Trevor Jones - Labrynth Soundtrack : a track in there really stuck with me. May have been “Goblin Battle”
I was also thinking Depeche Mode, but more in a “Enjoy the Silence” kinda way as you cradle your assault rifle/grenade launcher/flame thrower and you’re blowing everything around to smithereens - enter the irony…
Hehe, anybody else have a least one stanza of “Badger Badger Badger…Mushroom, Mushroom!” run through their head when considering evil songs?
Another vote for Holst’s Mars, Bringer of War
A third vote for Mars, Bringer of War. It’s the perfect processional song as the supervillain deploys his armor legions, his brand new battleship, or other BF weapon. (Oh wait, it was the theme for Expedition: Bismark.)
For a certain kind of villain, “I’ve got a pretty big list” (“Contadine, signorine, marchionesse, principesse”) from Motzart’s Don Giovanni is the perfect theme song.
For the particularly sarcastic villain, Liberty Bell March (aka Theme from Monty Python’s Flying Circus) is an effective entrance song.
What’s that song from Sleeping With The Enemy with Julia Roberts? That one gave me the creeps for a while.
I also think “MLK” from U2 would be a perfect quiet and bloody killers theme. Picture it playing in the background as you see his face incredibly devoid of emotion while standing over his last victim… the camera closing in on his blank stare.
… or the quiet yet disturbing Pink Floyd’s “Run Rabbit Run” (I think I got the title wrong) during the chase scene.
Some songs make me think of evil and horror and terrible villainy thanks to their use in movies and TV, even though their musical and lyrical content doesn’t have anything to do with it:
Stealers’ Wheel’s “Stuck In the Middle With You” from the torture scene in Reservoir Dogs
Tom Petty’s “American Girl” from the kidnapping scene in Silence of the Lambs
The Revels’ “Comanche” from the rape scene in Pulp Fiction
That old '50s song “Wonderful, Wonderful” from the intensely-creepy X-Files episode “Home”
Queen’s Princes of the Universe.
“You Better Run” from Pink Floyd’s The Wall. The intro sound - that Gilmourian guitar thing that sort of sounds like someone starting up a Harley - is creepy, as are the lyrics. “Welcome to the Machine” would be good, too, as well as just about any chapter of “Shine On You Crazy Diamond.” In fact, I think most Pink Floyd songs (Roger Waters era) would be suitable for chaotic mayhem, quiet plotting, or obsessive out-of-control evildoing.
my two tunes worth:
Guster - Airport Song
DJ Chris - Fetts Vette
Just to imagine it in a movie:
For a car chase scene: Jesus Built My Hotrod by *Ministry * (well, anything by Ministry sounds evil anyway)
For the build-up to the final shoot-out scene (á la Matrix #1 selection of weapons): Power of Lard by Lard, the first 3-4 minutes should be enough
Whip it up and Freedom of Choice by Devo for the teenage angst of the villain
For a cruising in his/hers evil-BAD-mobile looking for trouble: Bad to the Bone by George Thoroughgood and The Delaware Destroyers. If the car breaks down the Adam Sandler’s Ode to my Car will come in handy 
Santana’s Black Magic Woman or Evil Ways should fit in somewhere - evil boy meets future villainess? (or villain-ass?). I put a Spell on You by Screamin’ Jay Hawkins could also fit in this category, so would his Is you is or is you ain’t my baby though maybe more in the evil boy loses evil/nice girl.
And if the villain is an American then of course his theme song will be Chris Rock’s American Badass.
Since all the bad tunes belong to the bad guys I think we will have to figure out a way for squeezing in a few songs byThe Clash, such as The Magnicifient Seven (evil crew walking into the sunset?), Charlie can’t surf or Rock the Casbah - maybe for a non-amercian badass?
Nine Inch Nails’ Terrible lie and Head Like a Hole are just plain evil, good for plotting scenes.
For the final nuke-out scene I think Tom Waits’ The Earth Died Screaming will be perfect.
Other good sources (no scratch that, EVIL SOURCES): Dead Kennedy’s, Front 242, Metallica, B-52’s
And since Baldric was just posting, then the theme from Blackadder
A few of mine:
Dogs of War - Pink Floyd
Enter Sandman - Metallica (kind surprised no one’s mentioned this one yet)
Bad to the Bone - George Thorogood