American Psycho

American Psycho is probably one of the first movies that comes to mind when you think of music in horror movies and rightfully so. I’ll be the first to admit that I still dance like Patrick Bateman (Christian Bale) whenever Huey Lewis & The News “Hip To Be Square” comes on.
“I think their undisputed masterpiece is ‘Hip to be Square’, a song so catchy, most people probably don’t listen to the lyrics. But they should, because it’s not just about the pleasures of conformity, and the importance of trends, it’s also a personal statement about the band itself.”
The Final Girls

So the needle drops during a kill scene in a horror movie can bring some levity to the moment, maybe some dark humor.
The Final Girls isn’t one of those movies.
The Final Girls uses “Bette Davis Eyes” by Kim Carnes as a cue that we’re about to see Malin Akerman die on screen, either as Max’s mom, Amanda, or as the girl with a clipboard and a guitar in an 80’s camp slasher, Nancy.
And it hurts.
Rob Zombie’s Firefly Family Trilogy

Of course the guy who fronts a metal band would pick great songs to use in his movies.
Starting with House OF 1,000 Corpses, Bill (Rainn Wilson) gets strung up and tortured and transformed into Fish Boy while Baby (Sheri Moon Zombie) turns on the radio and dances around to “Brick House” by The Commodores. The finale of The Devil’s Rejects sees the trio doing their best impersonations of Butch Cassidy & The Sundance Kid while Lynyrd Skynyrd’s “Free Bird” plays ever so epically. Following the three miraculously surviving the barrage of bullets, their story continues as Otis (Bill Moseley), Baby, and Foxy (Richard Brake) flee to Mexico. With a bounty on their heads, they’re forced to fight for their lives as the sound of “In-A-Gadda-Da-Vida” by Iron Butterfly swells up to play over a slow-motion fight scene.
Rest In Peace Sid Haig, our Captain.
Happy Death Day and Happy Death Day 2U

Happy Death Day has become a surprise Blumhouse fan-favorite. In the first movie, Tree (Jessica Rothe) tries to narrow down the list of her possible killers as she’s stuck in a time loop where at the end of each day she gets stabbed…or held under water until she drowns…or blown up. As she makes her way down the list of suspects, while also chopping her hair and dying it pink and walking across the school’s courtyard naked, Demi Lovato’s “Confident” plays.
In Happy Death Day 2U, as Tree has to buy more time for her friends to figure out the correct algorithms to close the time loop in the correct dimension, it’s suggested that she kills herself before at the end of the day rather than waiting for her killer to get to her. Feeding into the dark, almost ironic humor that the Happy Death Day movies have developed, Paramore’s “Hard Times” plays over Tree’s suicide montage.
With hopes a third movie is still coming, now we can wonder what the murder/suicide montage song could be.
Pet Sematary

Stephen King is known to be a huge fan of punk pioneers The Ramones so he approached them to write the title song for the 1989 adaption of his novel Pet Sematary. King gave a copy of the book to bassist Dee Dee Ramone and then he came up with lyrics. The movie cuts to black as reanimated Rachel (Denise Crosby) picks up a knife to stab her grieving husband, Louis (Dale Midkiff), then as we hear him scream in terror over a black screen Johnny Ramone’s guitar riff kicks in.
The 2019 remake still uses the song “Pet Sematary” in the beginning of their credits sequence as a cover performed by Starcrawler.
At least that movie still used the song somehow.
Ma

Hearing about this kill scene is what made me want to watch Ma and it was well-worth it.
Driving her pickup truck, Sue Ann (a brilliant Octavia Spencer) plows down Mercedes (Missi Pyle) while she’s on her jog, leaves her in a twisted and bloody mess, tosses in calling her a “cunt” for good measure, then turns on the radio and “September” by Earth, Wind & Fire comes on.
Quite the celebratory kill song.
Shaun Of The Dead

“It’s on random.”
The jukebox at the Winchester Pub seems to personally attack Shaun (Simon Pegg) twice. First after he’s dumped by his girlfriend, Liz (Kate Ashfield), and “If You Leave Me Now” by Chicago begins to play. Secondly, as zombies are swarming the pub and backing all of them into a corner, “Don’t Stop Me Now” by Queen comes on and Shaun, Ed (Nick Frost), and Liz all grab pool cues and begin hitting the now zombiefied bartender to the beat of the song.
“David, kill the Queen! The jukebox!”
Return Of The Living Dead

“Do you wanna paaartaaay? It’s party time!”
“Party Time” by goth punk rockers 45 Grave has become like the theme song to 1985’s Return Of The Living Dead. The song plays twice in the movie and the second round is when the toxic rain begins to pour and dead bodies begin to rise from the dirt and, to quote the tagline on the poster, “They’re back from the grave and ready to party!”
Reservoir Dogs

Ok so it’s not a horror movie but it’s too good to not include on the list.
After the fuck up that was them trying to pull off a jewelry heist, the four remaining strangers return to their fallback spot (an empty warehouse) and they have brought back cop as a hostage. As tension rises amongst the group, suspecting one of their own is either a cop or is an informant, Mr. Blonde (Michael Madsen) decides to torture the cop, partially for fun and partially to try and get answers. “Stuck In The Middle With You” by Strealers Wheel plays on the radio as Mr. Blonde cuts off the cop’s ear, taps it like a microphone, and asks, “Is this thing on?”