Musical Spoiler

""Wait. The music cue just changed abruptly. Something's not right.""

- Shobu, Duel Masters

"Banjo: Hey Kazooie, there doesn't appear to be anyone in here. Kazooie: Oh yes there is. The music's changed. Every time that happens we always end up in a fight."

- Banjo Tooie

Sometimes, the first indication that something is about to happen is a change in the soundtrack. That's a Musical Spoiler.

The Musical Spoiler is particularly common in Video Games. For example:


 * If you think you've just started the final Boss Battle, listen to the music. If you're hearing the standard boss theme, you're probably up against The Dragon or the first form of a One-Winged Angel.
 * Similarly, if a plot-relevant fight uses the standard battle theme instead of the boss theme, you can relax -- this should be a short battle.
 * If you get your Fight Woosh but you don't get the normal battle music, you can also relax - you may be in a Fairy Battle.
 * In many Action RPGs, your first indication that an enemy is nearby is the battle theme beginning.
 * If the fight music is still playing, you haven't eliminated a threat entirely yet.

If the protagonist(s) enters a new area/room with seemingly no action going on and the music turns eerie or abruptly stops, then you know they're in trouble -- unless, of course, it stops via Record Needle Scratch or sounds like someone is Letting the Air Out of the Band, in which case it's time for a little comic relief.

Occasionally lampshaded, often by crossing over with Sorry I Left the BGM On, or by simply breaking the fourth wall as in the page quote. A Theme Music Power-Up is when the music indicates a character is about to do something utterly awesome.

Alternatively, at a sudden and unexpected death or other tragic event, tragic music may play too early and warn you that something tragic is about to happen.

Compare Foreboding Architecture, the visual equivalent. When the music is supposed to reveal information, that's Theme Song Reveal.

Unmarked spoilers ahead; beware.

Anime

 * In both series of Yu-Gi-Oh!, the music will tell you whether that apparently game-winning combo is actually going to finish the duel -- if so, the music swells. If not, it sticks with the standard BGM. Works better in the original Japanese.
 * Every once in a while it's subverted, though, and the music is cut out suddenly as the duel isn't finished after all. Very rare, however.
 * In Sailor Moon, the title character's attacks had their own background music. Occasionally she started her attack but the 'tense' or 'battle' music would continue, which was a sure sign the attack would fail (either because it was So Last Season or to show the enemy she was facing was not just any random monster of the day.)
 * In the Ghost in the Shell: Stand Alone Complex episode "Trial", the instrumental intro of I Can't be Cool is played over a speech by Togusa. I Can't be Cool is usually played when
 * The first Fullmetal Alchemist anime contains a subtle one. Near the end of the series, when Lyra is leading Rose to a church, Dante's motif begins to play.
 * In the Digimon series, if a digievolution is runing, but there's no music at all (or, sometimes, the regular fight or ambient track that was playing before), you can be sure the transformation will not be finished or turn to be a dark form instead of the regular one. Played more straight in the Adventure and Adventure 02, when there's less soundtrack options than the sequels.
 * Inverted in the trailer for Naruto Shippuden Episode 248- the normal musical lead-in for the trailer is replaced by screams of terror, as we finally get to see the Nine-Tailed Fox attack.

Fan Works

 * In Clear Skies 3, the Scottish funeral dirge "Flowers of the Forest" begins playing when

Film

 * Another non-game example: it's not very obvious, but Bernard Herrmann uses a leitmotif for "the big secret" in Citizen Kane that TOTALLY SPOILS said secret within, like, the first twenty minutes of the movie.
 * Done straight and subverted in Jaws. Every time the real shark appears, its classic theme plays; notably, it doesn't when the fake shark appears. Subverted in the second half of the movie, which plays the theme a few times as a red herring, and withholds the theme before the shark first encounters the Orca.
 * In 12 Monkeys, the "12 Monkeys" Leitmotif (a bandoneon song played by Astor Piazolla) plays during one of Brad Pitt's rants; this is the first clue that he's a member of The 12 Monkeys.

Live Action TV

 * Full House Music seems to be designed to be a Musical Spoiler.
 * In Law and Order, whenever music starts, you know something extremely plot-relevant is about to happen. To figure out what, just check the clock. Less than 20 minutes in? The plot thickens. Less than 3 minutes left? It's time for the Motive Rant.
 * The series also has a piece of music that is almost exclusively used when someone important to the case has committed suicide (or been murdered).
 * In the Doctor Who episode "Army of Ghosts", as soon as the Cybermen tell the Doctor that the Void Sphere doesn't belong to them, the theme music starts playing. Guess what comes out of the Sphere about a minute later.
 * Done all the time in the Dutch detective show Baantjer, to the extent that you can pay attention only when the "suspect is saying something important" music is playing and still get all the details on whodunit.
 * In Firefly, You could always tell when the Reavers were going to show up by the bass-heavy, metallic-sounding music that played along with their arrival. Best heard at around 2:35 here.
 * The Collector Ship Theme in Mass Effect 2 borrows heavily from the Reavers' music, and like there, it starts playing just before OH GOD WHERE'D THAT GIANT SHIP COME FROM?
 * Lampshaded on Mystery Science Theater 3000 in the episode The Hellcats. Crow is wondering if the main character can back out of a challenge he's just been faced with, and Tom replies, "No, it's too late, the music already started."
 * On Who's Still Standing?, every time the music starts to get louder, there's a commercial break coming in about 15 seconds, unless the show recent returned from commercial, in which case someone's going out on the current question.
 * NBC game shows in general have a nasty habit of using musical stings to telegraph the action; whether it's the question deliberation music on 1vs100 ramp up when a contestant is about to lock in an answer, or Identity's music ending just as an answer reveal is about to take place, savvy viewers will be able to know what's going to happen just by paying attention to the music beds.

New Media

 * Parodied in this Onion piece, where ominous music starts playing across the USA, sending the media into high alert.

Tabletop Games

 * In the tabletop RPG In Nomine, followers of Nybbas, the Demon Prince of Mass Media, can gain the supernatural ability to hear background music. Changes in the background music can warn them of danger.

Video Games

 * If the music in Halo makes you think "How did they MAKE those sounds?!" then load your shot gun and bare your Energy Sword, you're about to be Flooded.
 * In Chrono Trigger, you know when Lucca, Frog, Robo, or Ayla is about to do something cool because their Leitmotif starts playing.
 * Although in his first appearance (a Big Damn Heroes moment), Frog uses Lucca's Leitmotif.
 * Poor Lucca's theme is so awesome that the developers simply stole it from her. It serves as a general victory or something-awesome theme, especially in Chrono Cross.
 * If you listen to Schala's theme the first few notes
 * How do you know that the Undersea Palace is important to the plot? Plenty of Mook battles, but no battle music. The Palace's background theme plays throughout.
 * In Phoenix Wright: Ace Attorney and its series, if you make a correct "Objection!", the music stops. If the music continues, you know you messed up even before the judge yells at you and takes away part of your Life Meter.
 * Also played for laughs. Near the end of one case ,
 * In Ace Attorney Investigations, when Confrontation: Presto plays, you know whoever you're cross-examining is the killer. The second game subverts this. It still signifies a Wham! Episode, but that doesn't necissarily mean you're cross-examining the killer.
 * In Castlevania: Symphony of the Night, you know you've walked into a boss room (it doesn't have special doors like later installments) when the music stops.
 * It doesn't happen for the boss in the Long Library, though.
 * In Final Fantasy IX, the intro to the "Fairy Battle" theme is meant to sound just like the intro for a standard battle, probably to avoid the Musical Spoiler -- but the instruments are different enough that if you're paying even a bit of attention, you can tell the difference.
 * Not avoided at all in Final Fantasy VII if you have the Chocobo Lure materia on. You will know right away whether there's a chocobo in the encounter or not, even while the battle transition is still happening.
 * In XIII-2, a slightly different victory theme plays if you achieved a 5-star ranking on a battle. Since the victory music starts up the moment the lat enemy has been killed, you know how well you did long before getting to see your actual rank.
 * Akitoshi Kawazu has a lot of fun playing with this trope in his work for Square:
 * In SaGa II (Final Fantasy Legend II in the U.S.), the heroes are spying on a secret meeting between several villains. As soon as the villains spill the beans on their nefarious underworld dealings and the Heroic Tune fires up. The villains all start looking around, asking "Where's that music coming from?!", then you bust in on them.
 * In Final Fantasy Crystal Chronicles Echoes of Time, the party reaches the end of a library-themed dungeon and runs into a spacious arena-style gallery as the boss fight music strikes up, then peters out as the heroes look around and no boss monster is evident.
 * Similarly, in Dragon Quest IV, Chapter 3, Taloon will sometimes run into traveling merchants. Since these traveling merchants are accompanied by the town theme instead of the standard battle theme, you can tell you're OK as soon as the music starts.
 * Lampshaded in Final Fantasy Mystic Quest. Every time Tristam is about to make an appearance, his Leitmotif plays, and the main character reacts in surprise and starts looking around for him.
 * At one point in Metal Gear Solid, your comrades actually advise you to listen to the volume of the background music in order to judge whether a helicopter is near you or not.
 * Plus Snake actually wonders aloud "What happened to the music?" shortly before the battle against Psycho Mantis.
 * Given that Psycho Mantis' entire schtick is that he has No Fourth Wall (you beat him by ) this is unsurprising.
 * And then, as the voice actor credits roll at the end of MGS4 you may be wondering "Why is Leitmotif playing?", then, "Why does  have a voice actor credit?", and then, ""
 * In Banjo-Tooie, an ominous theme (aptly named "There Comes Trouble...") always starts playing when the duo is about to face a Boss Battle. Eventually, upon entering a curiously empty room, Kazooie points this out by declaring: "The music's changed. Every time that happens we always end up in a fight," before, oddly enough, fighting the Goldfish Poop Gang for the third time.
 * Subverted in the same game, in Terrydactyland. Considering the number of massive dinosaurs about, it helps add to the grandeur of the area, but it's still bizarre. An area obstacle (to be fair, an irritatingly difficult one) gets the ominous theme and boss description (Triassic Steamroller). A minigame gets the ominous theme and boss description (Stomach-Cramped Carnivore). A completely harmless NPC gets the ominous th... no, no theme, but he still gets a description (Seeker of Beverages). Even the actual boss of the area becomes a friendly NPC after his defeat.
 * Egregious in Deus Ex, where the music is the best way of knowing if you are detected by the enemy.
 * Also Splinter Cell, the best way to know if you've been seen is if the music suddenly starts. Being a stealth game, the music is usually off. Also - not sure if you've killed everyone after being seen? Listen to the music. Especially in the first game, it'll start winding down the moment you're in the clear.
 * In Painkiller, you know when enemies are about to attack because the heavy metal soundtrack will kick on, and you know you've defeated all the enemies in the current area when the music fades away.
 * Same goes to music in Serious Sam.
 * Similarly, in Kingdom Hearts, the music changes when you get within a certain distance of Heartless -- whether you can see them or not.
 * Vanitas' Battle Theme has bits of both and  music in it.
 * The music in Donkey Kong Jungle Beat changes constantly to indicate the presence of different enemies, enemy vulnerability windows, combos, combo breaks and boss-damaging flurries.
 * In Dragon Quest VIII, if you successfully flee from a battle, your first indication is that the music stops.
 * In the third Prince of Persia game the music changes whenever you're close to an enemy, even when you can't see them. This is actually rather helpful, but pushes the Willing Suspension of Disbelief just a bit further than usual.
 * In Prince of Persia 2, however, you hear a menacing chord every time you drink a potion--even if it's a life-extending or healing potion. Someone didn't think that one completely through.
 * The 3D Zelda games all replace the normal music with a combat theme when an enemy is near. In addition, The Legend of Zelda Twilight Princess also had a special remix of the Hyrule Field overworld theme that plays whenever you've exposed an enemy weakpoint, and is generally your cue to commence button mashing (or Wiimote waggling) to get in as many sword-hits as possible before the boss recovers.
 * In addition, in The Legend of Zelda Phantom Hourglass, the easy way to tell if you're being chased by the Phantoms in Temple of the Ocean King (other than the giant "I HAVE YOU NOW" or whatever across the bottom of the screen) is by listening to the music changes. When the ominous music goes away, you know they've stopped chasing you.
 * Boss battle themes don't usually spoil since they only start after the enemy has been "introduced" to you. However, the music stops when you first enter a boss room, and the series isn't known to throw you into unexpected boss battles. Also, the boss music itself usually stops once you've landed the final hit on the boss, signifying that you've beaten it (though the fact that the game also switches to a cutscene of the boss dying can be a spoiler before even that).
 * Even the very first The Legend of Zelda, which didn't use boss music, warned you when you were approaching boss territory. If any of the adjacent rooms held the Dungeons boss there would be "roaring" sounds every few seconds. Though some boss like monsters would make those sounds while onscreen anyway.
 * In The Legend of Zelda Skyward Sword, the melody of the Goddess' Song, the game's main theme, is Zelda's Lullaby played backwards, foreshadowing the fact that.
 * There's a severe difference in style between the normal background music and the fight music in Devil May Cry. Thus, if you enter an area and the music abruptly shifts gears, get your sword out. This is especially true for the third game, where the fight music has vocals.
 * Occasionally, when you kill an enemy in God Hand, their soul becomes a demon and attacks you. You'll know it when it happens, even if the enemy is offscreen, because the music suddenly switches to a distinctive guitar sequence (or, if one of the horribly powerful Four-Armed Demons arrives, an orchestra).
 * In Tales of Symphonia, if it wasn't obvious that the thing you went to the Latheon Gorge to get has a boss guarding it by genre alone, the music stops when the enter the room.
 * In Cave Story,
 * Even before that, you can be certain that because of the music.
 * An earlier boss battle subverts it. The player activates a robot which attempts to destroy him, and in the robot's dialogue the standard boss music starts playing. Then the music is suddenly cut off as Balrog steps on the robot.
 * The Sonic Advance Trilogy has the "Boss Pinch". When a boss hits critical HP, the music suddenly changes to reflect it. The first games featured a total different tune for the Boss Pinch but in the third game, it's actually an awesomely frantic remix of the regular boss theme.
 * The same thing happens in Bomberman Generation. The music switches to a variation of the Standard (Multiplayer) Battle theme when a boss is in critical condition.
 * Sonic Generations, if you know your Sonic music. While standing outside a stage / boss, a medley will play. If you can correctly guess where the medley comes from, then you have an idea of what to expect.
 * Averted for the last two bosses. The sixth boss plays a remix of E.G.G.M.A.N. from Sonic Adventure 2, and the final boss plays no music at all.
 * Planescape: Torment uses this occasionally, especially in The Very Definitely Final Dungeon. A few seconds into the area's music.
 * As you enter the roof of the Temple of the Ancients, in Knights of the Old Republic, 's theme music plays. It's not very long before you meet the person in question.
 * Then, of course, there's the fact that Darth Revan's theme music plays
 * Ah, but remember: at that point of the game - the first time through, of course) - Revan's theme hasn't played yet (well, not in actual relation to Revan).
 * Parasite Eve does this fairly often; when a boss is in the next room or a major event has happened, the music will stop. Also occurs during the Bonus Dungeon when you arrive in a very large room where a boss would be.
 * Hostile NPCs (and animals) in Gothic tend to chase the player if he tries to flee from a fight. It's possible to tell when they've given up the chase without having to turn and look, because the dramatic music stops playing.
 * You can tell how close you are to winning or losing a boss fight (on foot) in Skies of Arcadia by how panicked or triumphant the music sounds.
 * Morrowind and Oblivion, in The Elder Scrolls series, switch to battle music whenever you initiate combat and whenever an enemy starts chasing you -- regardless of whether you've spotted the enemy.
 * Same thing in Fallout 3, which is also by Bethesda.
 * Read, THOSE GODDAMN CLIFF RACERS. Only in Morrowind though, but the ENTIRE Elder Scrolls community HATES them with the burning passion of a thousand suns, simply because they can see you from MILES AWAY and will follow you WHERE EVER YOU FUCKING GO. Once you either A) Leave the mountain range where they are, B) Get far enough away that they stop chasing you or C) Kill them, they stop following you (though option C is obvious).
 * You contracted Hell Joint.
 * The dragons of Skyrim are practically the spiritual successors to the cliff racers. And come with convenient pseudo-dramatic nordic chanting to let you know annoyance-from-above is on its way. While they're not so prone to chasing you across the land, trying to go about your business while a giant sky-lizard tries to burn you, your horse and all the NPCs in town to a crisp can be rather tiresome. The lack of acrobatics / jump spells / levitation in this generation doesn't make things any easier.
 * Left 4 Dead has musical cues for a lot of things. Zombie hordes attacking, special events, atmosphere cues, etc. Most prominent of all would be the leitmotif that kicks in when certain special zombies are nearby. And yes, people have already figured out how to replace said music with renditions of Yakety Sax.
 * Here are the Witch and Tank themes. If you hear them in gameplay, you know that you're in for a near-death experience.
 * The freeware PC game Survival Crisis Z varies the number of instruments used for its background music based on the number and type of enemies near the player, ranging from a simple bass beat to an almost-overwhelming cacophony of industrial, glass, and synthetic noise. Given that zombies can randomly appear en masse just by entering and leaving buildings, it's not at all uncommon to walk through a door and instantly know you're in trouble by virtue of several additional instruments kicking in.
 * Wonder Boy in Monster World was an exception to the boss rule: even the second stage of the final boss used one of the stock boss tracks, with original music only coming in for the end credits.
 * Uncharted Drakes Fortune plays scarier action music when you go into fights. Since bad guys come in waves and sometimes hide in weird places, you can occasionally lose track of one or two enemies. Thankfully the music doesn't change back to the ambient sound effects until you've killed them all, so you know to use caution going around corners and such.
 * Super Mario Galaxy has an example heard in a few cases, there's a certain ominous theme appropriately titled "Danger Ahead" in the small section of the level before a boss battle, as can be seen when on the UFO before fighting Topmaniac, the small section of level before Tarantox and before the first King Kaliente battle (although really, it's kinda ironic the only bosses this happens for are those that don't need the warning because they're generally easy). Similarly, there's a kind of dead obvious giveaway of the boss battle about to start in Bowser Jr's reactor levels, in that his theme tune starts just before the boss starts attacking (and Bowser Jr himself will fly in and taunt you.)
 * Super Mario Galaxy and its sequel also use a method similar to Twilight Princess, in that during the fights with Bowser, Ominous Latin Chanting will be added to the music when he's vulnerable to attack.
 * Galaxy subverts this with Bowser Jr's appearance in the final level, where at first it looks like you're going to fight him before actually fighting Bowser for the last time, but it turns out that you actually fight Bowser directly instead. Although he does rain meteors down on the stairway.
 * "Danger Ahead" was remixed in Super Mario Galaxy 2, but it only played in Bowser Jr's Boom Bunker.
 * The presence of enemies in F.E.A.R. and its sequel can often be given away by changes in the music and the occasional dramatic sting. Especially helpful for revealing Replica Assassins before they kill your face.
 * In La-Mulana, if you enter a boss room before unlocking the boss, the area music keeps playing. Once you unlock the boss, entering the room replaces the area music with the pre-boss music.
 * In Ace Combat 6, if the music stops without "Mission Accomplished" flashing on the screen, it is guaranteed that Strigon Team, cruise missiles, or both are going to show up in the next few seconds.
 * In the Tetris the Grand Master series, if the music cuts out, the next section is going to have a Difficulty Spike. In TGM1 and TGM2's Master mode, this famously first happens at halfway through the game--once you get to the next section, pieces will start dropping instantly. In TGM3, this can happen as early as three-tenths into the game if you're fast enough
 * Super Robot Wars generally started up an easily memorizable musical cue that comes in about two seconds before either The Cavalry arrives or you're about to get swarmed by a dozen new units right as you'd gotten by the last wave through the skin of your teeth.
 * Plus many Original Generation characters have their own musical theme that plays when they take a turn in battle. Original enemies also have this, and it usually overrides the heroes theme. Take a good listen. If the music is inspiring or heroic, then they'll be pulling a Heel Face Turn before the end. There's no way that "Trombe" or "I am Baran Doban" could belong to total villains after all. And Shura General Alion's joining of you would have come right the hell out of nowhere, since he didn't do this in the original game, were it not for his very non villainous music playing every time you fight him before hand. There are only two exceptions. Shu's sinister and epic "Dark Prison" is blaring whether he's shooting at you or saving your hide, and Alpha 3's Hazal Gozzo has the oddly cheerful "Clown Master" as his theme, despite being a Complete Monster and never even has a chance to join you.
 * Most prominent example comes from Super Robot Wars W. The first Database member that appeared is Aria Advance, and her leitmotif, if listened closely, is a rearrangements of Kazuma's leitmotif.
 * In Alien vs. Predator 2, xenomorph encounters would be accompanied by the orchestral soundtrack...of AvP 1. For some reason the original installment, though packaged with a soundtrack, never utilized it in-game, which is why it is much, much scarier than the sequel.
 * This is also the reason that the actual film Alien cut back on its original bombastic musical score, replacing it with mostly silence.
 * The original score was cut back... but most of the film is actually scored. It's just so subtle and nuanced that it contributes to the atmosphere without you realising. It's still an aversion of the trope, just an aversion born of ridiculous amounts of compositional skill.
 * Aliens vs. Predator (2010) followed the example of its 1999 predecessor, leaving the score mostly unaltered except for certain scripted events. Arguably less effective, however, as the 1999 game used silence to emulate the score of Alien as described above, making it one of the creepiest games to date, matching the likes of Silent Hill.
 * Averted in Dual Orb II... for the simple reason that the developers didn't bother to make more than one battle theme for the entire game. Even the final battle uses the standard music.
 * In Ico, the music is your first warning that the shadow-wraiths are approaching, or that some are still lurking nearby even if you can't see them.
 * In Earthbound, you know a visit to the Threed Sunset Hotel is about to go very, very wrong when the usual hotel theme is distorted into an eerie parody of itself.
 * The music in Syndicate shifts to a much more tense and fast-paced theme when an enemy cyborg is nearby. The manual advises the player to use the music as an early warning system for imminent combat.
 * In Call of Duty: Modern Warfare 2, a deep note followed by ominous music means a Juggernaut is after you. Be very afraid.
 * Because Tomb Raider games tend to have ambient soundtracks for levels, musical cues become key means of distinguishing when a trap, puzzle, or hazard is nearby. And the more dramatic the cue, the more imminent the danger is (sometimes you will only have seconds to live unless you react quickly).
 * Dead Space. It's not over until the music goes away. This makes it rather disorienting to fight in a vacuum, where the battle music is typically absent.
 * In Metroid Fusion you can often tell that you're nearing a boss battle when a certain piece of ominous music plays. The soundtrack is non-apologetic about this, calling itself "Tension Before a Confrontation".
 * In Professor Layton and the Curious Village, the professor's theme has a subtle ticking as punctuation. This foreshadows the revelation that
 * Averted when Layton's about to reveal something about the mystery, the music stops and says his stuff.
 * Mother 3 has one that, if you're paying attention to it, hints at the twist that
 * Additionally, all player characters and enemies have a certain instrument or sound (electric guitars, horns, animal noises, etc.) that plays when they attack, incorporated into the "sound battle" system. Because of this system, the player characters' combo instruments tend to stand out a bit more than the enemies', so it's easy to miss In a similar fashion, knowing that  helps to remove any lingering doubt you might conceivably have as to Lucky's true identity, though this isn't as strong (or, indeed, as obscure) as the former example.
 * In Yoshis Island, the room before (or with, in many cases) the boss always has the same ominous background music playing to indicate a battle will start. Comes with a long corridor for build up.
 * Both the Penumbra series and its spiritual successor Amnesia the Dark Descent play this trope straight. Hide or run until the caution/danger music stops playing and the enemies are guaranteed to have left the area.
 * Bayonetta example: One of the very last boss fights is accompanied by a song named Needless to say, a single look at the game's soundtrack blows that particular reveal right out the window.
 * In certain Kirby games (such as Nightmare in Dreamland), the music completely stops before a boss room. That and there's usually a few recovery items and free copy abilities.
 * Used in many ways in the Silent Hill games. If you hear particularly ominous ambient noise/music, it usually means enemies are nearby or something big such as a Boss Battle or transition to the Dark World is about to happen. However, sometimes it's just a false scare.
 * Resident Evil 3 Nemesis: When "Feel The Tense" starts up, Nemesis has entered the area. In RE 2 and others, if the music is replaced by silence, it means something such as a Licker is going to jump out at you. In fact, more or less all the RE games use this trope in some way.
 * At one point in the Bonus Dungeon in Shin Megami Tensei Nocturne, Dante will hunt the Demifiend through a series of tunnels. If his theme replaces the background music, it means he's close to finding you.
 * The more difficult bosses in Ys IV: The Dawn of Ys use "A Great Ordeal" for their battle theme, as opposed to "Battle 58".
 * In Ys VI, the music is silenced before the first boss appears.
 * In Iron Tank, the music changes to static noise, or sometimes the boss music itself, shortly before a boss fight.
 * In Syphon Filter, the music intensifies when the enemy is targeting you, and calms down when they lose sight of you. The later games such as Omega Strain have special music themes for high-ranking terrorists or Timed Mission objectives.
 * Mass Effect 1: It's not much of a spoiler, per se (talking to anyone suggests basically the same thing), but when the time comes to have it out with Wrex on Virmire, even walking towards him turns on the Ominous Drumroll.
 * Haunting Ground uses this specifically as a game mechanic: Belli castle has its ambient music, and it has the chase music for each of Fiona's pursuers. However, because those pursuers are actively searching for Fiona, they're running around the castle the same as she is. Whenever one of them is in a room adjacent to the one Fiona's in, the music slowly fades out into complete silence, leading to one of the best uses of "Wait, it's too quiet" ever to be visited on a player.
 * Appears accidentally in Dungeons of Dredmor. If the normal background music stops when you open the door to a room, instead of changing quickly when you walk through the door, it just means the game is having trouble loading both the massive amounts of enemies in the room and the awesome 'Monster Zoo!' theme.
 * In bad ending of Katawa Shoujo, the ominous "Cold Iron" theme starts playing as the last scene begins, before things start going wrong.
 * Wrong for Hisao at least. Nothing could prepare the player for the awakening of.
 * The music in Battlestar Galactica Online picks up when you engage in behaviour that triggers the Threat indicator. Unfortunately, it's easy to trigger the indicator by accident.
 * Psychonauts. For just one or two seconds at a time in the BGM during the fight with  the BGM from  's mind will suddenly play quietly, and then shut off again, cluing you in that he's behind it all. Although, you may have known already, and the full revelation does hit you in the face a few moments after the boss fight.
 * Psychonauts. For just one or two seconds at a time in the BGM during the fight with  the BGM from  's mind will suddenly play quietly, and then shut off again, cluing you in that he's behind it all. Although, you may have known already, and the full revelation does hit you in the face a few moments after the boss fight.

Webcomics

 * In the MS Paint Adventures series Homestuck, in order to warn the viewer that the next update will have music in it, every flash update with music will start with an [S] in the link to the page. Most of these updates are a Crowning Moment of Awesome (with corresponding Crowning Music of Awesome).
 * This is sometimes subverted however, as there are plenty of joke updates that don't involve said Crowning Moment of Awesome, though these are often Crowning Moment of Funny.
 * The flashes are often made with music that has been public for a long time. Most of the time this isn't spoilery, as the music is straightforward - dramatic, sad, awesome, etc. However, in one case it was. The flash
 * And then there's Intermission 2 which uses a previously released song entitled.

Western Animation

 * Partial version in Batman: Mask of the Phantasm: an unusually distinct bit of music plays when we see what appears to be an unimportant mob henchman. Sure enough
 * Perchance to Dream uses a modified version of  Leitmotif as a musical hint towards.
 * SpongeBob SquarePants: "Can't you hear the music? That?s a 4/4 string ostinato in D minor! Every sailor knows that means death!"
 * "Our friendship will never die..."

Video Games

 * Chrono Trigger has a funny pair of subversions involving Ozzie. The first time you meet him, he brings up a series of monsters with a crank, and they drop onto a conveyor belt. The battle music starts, and your characters even get into their battle poses... then the enemies fall into a pit at the other end of the conveyor belt. Insert "record winding down" sound here. Then, the second time you meet him, the boss theme starts playing, and then
 * And who can forget Dalton? When he epically turns the Epoch into the "Aero-Dalton Imperial", Crono's "fanfare" theme starts up, prompting Dalton to yell, "No, no, no, no...! Stop the music!" The music then changes into "A Spot of Crisis", a tense theme, and he says, "Ha! There we go! Ready for takeoff!"
 * In Dragon Quest III, there are exactly three battle themes. Most bosses don't get their own... but..., gets a special theme.
 * Not so in Dragon Warrior 3, where that same boss gets the same boss music. Of course, since the NES game shipped with a full walkthrough in the manual, it probably didn't surprise anyone.
 * The final boss of The Legend of Zelda: Link's Awakening had special music for its first forms, but used the mini-boss music for its final form.
 * Also, in Twilight Princess, in Hyrule Castle, the final dungeon, aside from the mini-boss songs that play when fighting a Darknut and, no danger music plays while fighting enemies, adding to the mounting climactic suspense.
 * Both the Ganondorf and Ganon battles in Ocarina of Time have their own unique theme, making the first form (Ganondorf) seem like the final battle.
 * The Simpsons had it in the X-Files episode when a mysterious music cue is revealed to be coming from a passing bus in which an orchestra is playing.
 * Final Fantasy VII avoids giving Sephiroth's first form standard music in the final battle by having unique songs for his first two forms: "The Birth of a God" for Bizzaro Sephiroth and "One Winged Angel" for Safer Sephiroth.
 * In the Greenwood area of Soul Blazer, there is a dog who, when talked to, will tell you that "today's special is...you!" accompanied by an abrupt end to the background music. The dog will then proceed to explain that he was only joking, and the background music starts up again.
 * In Shining in the Darkness, despite the fact that the fight against The Dragon had a special boss theme, the final boss uses the normal combat theme you've heard all game. That is, until he gets serious...
 * Every plot-required boss battle in The World Ends With You is accompanied by normal battle music.
 * With the exception of the final boss, of course, who gets his own unique remix of Twister. Every other non-boss battle randomly uses music.
 * The first Xenosaga game uses the same battle music for every fight. Common enemies and bosses have the same tune. The sole exception is the final boss, who has its own theme.
 * Scratches subverts it near the beginning, on the first time you  Later its played straight when , also on Last Visit after solving all puzzles
 * In Teenage Mutant Ninja Turtles, a first-time player will probably think that they're fighting the final Boss Battle when they fight Shredder for the first time, and when they fight Krang. (The final Boss Battle is a rematch between the Turtles and Shredder.) Both of these bosses have a special Boss Battle music of their own to help give the player this illusion.
 * Mushihime-sama Futari's Final Boss gets its own theme, but on Ultra difficulty, the True Final Boss uses the regular boss battle music. That is, unless you're playing Black Label (which replaces Ultra mode with God mode), in which case the TFB gets some...rather unfitting music for a climatic boss battle.
 * In Golden Sun, the battle against Saturos and Menardi has its own unique theme, and one might think they're the Final Boss. Then they turn into a A GIANT TWO-HEADED DRAGON that dwarfs the party (and all other enemies up to this point) and actually shatters the screen as the combat intro.
 * Amagon's fourth stage keeps the same creepy music all the way through, even when in Super Mode or fighting the boss.
 * In Blaster Master, the Final Boss reuses the Stage 7 music.
 * In the arcade version of Super Contra, the penultimate boss gets its own theme, but the final boss just uses the main stage music.
 * In Mega Man 2, the final boss against the alien hologram has the same music as every other boss.