Villain Song/Professional Wrestling

Just about every heel wrestler's entrance theme, if it has lyrics, tends to be a Villain Song, but for some specific examples...

WWE wrestler Triple H's entrance theme, "The Game", is largely a Villain Song, sung by Motorhead from Triple H's point-of-view. It's three-and-a-half minutes of gloating about how Trips is the baddest of the bad and controls the WWE with an iron fist. Lemmy even throws in an Evil Laugh or two along the way.
Randy Orton's current theme is an awesome Villain Song.
The Undertaker's theme - BONG. *cue the druids, ominous Latin chanting, and one hell of a creepy Evil Laugh*
Shawn Michaels' theme, "Sexy Boy."
The Million Dollar Man" Ted Dibiase. (Evil laugh), MONEY MONEY MONEY MONEY MONEY, "Everybody's got a price!"
A semi-subversion: "Stand Back" was sung by Vince McMahon with the original intention to be used as Andre the Giant's song (and was actually used as such for a promo video and in the NES Wrestlemania game), but wound up being used for McMahon himself, who wasn't actually a villain at the time. (His on-screen persona was a face-biased announcer, nothing more) That changed a few years later, when he got a new persona and a new theme:
"'Cause you've got.... NO CHANCE!" To quote Bill Simmons:

I'd want to come out to Vince McMahon's "No Chance" song, just so I could perform the "I have complete and utter disdain for everyone in this building, and that's why I'm walking with an exaggerated swagger and frowning" routine while 20,000 people lustily boo me. That seems like more fun than humans should be allowed.

As much of a douche the Miz is...his song fits the trope.
- "I came to PLAY! There's a price to pay, time for you to get down on your knees and pray. Say GOODBYE to the good ole days, they're never coming back, watch your future fade.
  - His Wrestlemania 27 promo song, "Hate Me Now", is even better. Here it is, with Miz's current titantron.
In the early 90s The Texas Hangmen had a pretty awesome one to introduce them to the USWA it helped establish how Ax Crazy they were.
- "CLOTHESLINE will break your neck! The match is over and your body's a wreck. POWERSLAM will put you out! Havok and mayhem is what we're about!"
Drew McIntyre's star may have faded, but his theme fits to the T.

What's that metronome I hear?
Perhaps the end...is drawing near?
You never hear the shot, that takes you down.
Out of time...so say goodbye.
What is yours....now is mine.
And I DREAM BROKEN DREAMS!
I make them come true...
I make them for youuuu.

The Honky Tonk Man: His 50s-styled themed entrance song, the narcissistic "Honky Tonk Man." He's cool, he's cocky, he's b-b-b-b-b-b-b-baaaaaaad.
The Mountie: Jacques Rougeau Jr.'s heel marching tune, "The Mountie." When Rougeau began teaming with Pierre Oulette as part of The Quebecers, the tune was changed to "We're Not the Mounties" but – aside from minor lyrical differences and the vocal track replaced with a duet – kept pretty much intact.