Theme Song Reveal

Music is a powerful tool. With a good musical director, a Narm becomes a Hallelujah Moment, a dull comedy sequence becomes hilarious, and a theme tune gets stuck on your head for days.

The Theme Song Reveal is when it goes a little further.

In the Theme Song Reveal, actual elements of the plot are hinted at, suggested, or outright stated, and the music is the giveaway. It's a Musical Spoiler, but an intentional one, and one that gives away plot details.

Say you're watching your favourite TV show, and Bob and Chris encounter a Black Cloak with a mask. They don't know who it is. But you do, because you bought the first season soundtrack and listened to it enough to know it all by heart, and you know that whenever Black Cloak does anything more exciting than walking down a hallway, Alice's Theme plays softly in the background. Alice can change her outfit, but no amount of plastic surgery can change her theme music.

Used well, this trope can serve as a much-needed nod to the musically-observant, or to everyone with a working set of ears, depending on the way music is used in the work as a whole. Used poorly, it might result in a hint no-one notices, or a painful Foreshadowing anvil.

It seems to be used more in video games, where the use of soundtrack is more prominent, in all but the most cinematic Cutscenes.

See also Musical Spoiler, the unintentional version of this trope.

Anime and Manga

 * Digimon Adventure 02 had Myotismon's theme play when Malo Myotismon's face appears as a partial silhouette, an episode before he revealed himself.
 * When Archer cuts loose with his Unlimited Blade Works in Fate/stay night, a more badass version of  starts playing, signifying that this guy is.
 * It played during, as well as   in the UBW route and against  in the HF route. In fact, the game only uses the song for * one* of Archer's scenes in all three routes, and even then it starts playing when he's losing. Its usage in the anime is really more a Fridge Brilliance moment of Foreshadowing for anyone who is familiar with the game.
 * An example of this is in Gankutsuou's theme song, which tells the story of Edmond Dantes and the motive behind his Roaring Rampage of Revenge before it's revealed at the end of the anime. It only avoids being a complete spoiler of the story by not identifying the song with his character.

Film

 * In the Star Wars prequels, there's brief snatches of the distinctive Imperial March in the soundtrack, poignantly reminding the viewer of Anakin's eventual fate. In fact, "Anakin's Theme" is essentially a more innocent version of the March.
 * Also, the triumphant, joyous fanfare at the end of The Phantom Menace is an alternate arrangement of the Emperor's theme from Return of the Jedi.
 * One letter: M.

Live-Action TV

 * "Martha's Theme" in Doctor Who was specifically written to sound a little like the theme tune of the Doctor's previous companion, Rose, and to share its opening notes with the "Doctor's Theme", thus presenting the viewers with two subtle cues as to Martha's role in the plot of Series 3.
 * When the Doctor and Professor Yana, aka.  first meet in "Utopia", "This is Gallifrey (Our Childhood, Our Home)" plays in the background.
 * Speaking of "Rose's Theme", it became so identified with that character, that in at least two instances (in which Rose reappeared in the series after having left earlier) it was the only identifier used for the character, with her name not even being uttered for the benefit of those not familiar with the established canon.
 * In series 6, the same track plays during in "The Impossible Astronaut" and  in "A Good Man Goes to War", foreshadowing that . The track's name on the soundtrack is.
 * The opening credits/theme of Fringe are changed to suit the episode. If it's a flashback, then an '80's style font is used, the technology words used are from that era and the theme has an electronic tone. If it's set in the alternate universe, then everything is red instead of the usual blue of our own universe and the technology words reflect that alternate world.
 * In "Life On Mars," Sam Tyler is listening to the titular David Bowie song on his iPod when he gets into his car accident. He spends the rest of the next two series taking a look at the lawman beating up the wrong guy, and trying to make sense of his life while feeling like he's on another planet.
 * In the series finale of Smallville stings of the classic John Williams Superman theme are used throughout the episode to hint at where things are headed, with the entire theme bursting forth at the appropriate moment.

Theatre

 * Opera example: In Richard Wagner's Die Walküre (from his gargantuan Ring cycle ), the eponymous heroine Brünnhilde tells Sieglinde that this Damsel in Distress is pregnant -- but the music reveals the unborn child's identity through the use of the Siegfried Leitmotif, which is next encountered (and clarified) in the next opera of the cycle (Siegfried, naturally).
 * An even better example from the first act of the same opera: when Siegmund is telling the story of how his father mysteriously vanished, the trombones very quietly play the Valhalla theme (which is also Wotan's theme). In the following scene, Sieglinde describes an old man in gray who came to her wedding to Hunding and stuck a sword in the ash tree, while the same Leitmotif plays.
 * In Götterdämmerung, when Hagen is singing to Gunther about being only his half-brother, Alberich's motif is played, pointing to the fact that Hagen is Alberich's son, revealed later in the opera.
 * In Sweeney Todd: The Demon Barber of Fleet Street, an instrumental version of the part of "Epiphany" in which  can be heard while he.
 * And if that's not enough, the scene where  in the theatrical production  . (This was a late addition to the show, and so isn't on the original cast recording. It's apparently optional material, like the tooth-pulling contest and Judge Turpin's song.)
 * Older Than Print: In the 12th century Latin Ludus de Herode (The Play of Herod) King Herod and his son sing a song about their fear of and desire to destroy the new-born Christ. Then, when Herod calls the Magi in and instructs them diligently to seek out the Child, he sings the line "that I too, coming, may adore Him" to the melody of his Villain Song.

Video Games

 * In Star Wars: Knights of the Old Republic, theme plays as you reach the crest of the temple on Rakata Prime. Also an example of Dissonant Serenity.
 * The fact that 's theme plays during character creation also certainly foreshadows a few things...
 * In Phoenix Wright Ace Attorney: Trials and Tribulations, it's obvious pretty much instantly who  really is, but, when  starts playing, the player's suspicions are finally confirmed.
 * A smaller version is Ron DeLite. While the first part of the case is an attempt to prove that he is not the Gentleman Thief Mask* DeMasque, the fact that Ron's theme plays when the thief is mentioned doesn't leave much room for doubt.
 * Iris may be wearing a hood when you first encounter her, but the Background Music alone is enough to ensure you: "This girl is the Dahlia lookalike Phoenix' searching for!"
 * Phoenix himself gets a variation of this in the fourth game. The mysterious client in the grey parker with the blue beanie might have been revealed to be him already half a case prior to this, but many players were unwilling to accept this as the truth - until his theme song started playing, at which point he uses his iconic Objection-stance.
 * Ace Attorney Investigations has a short cameo for Shi-Long Lang during a flashback case where he appears as a mysterious police officer, but his theme song makes it clear who he really is.
 * In Metal Gear Solid 2 Sons of Liberty, the masked, unidentified ninja dives for Ocelot's arm, and the music plays the sharp opening bars of 's theme, providing a clue for the musically observant as to who the ninja is before the official reveal. This one was in a very cinematic cutscene and was short - it was so subtle that everyone who hadn't shelled out for the OST (or watched the Making Of where the trick was blatantly pointed out by the announcer) probably didn't notice it.
 * In Metal Gear Solid 4 Guns of the Patriots, 's theme plays over the voice actor credits...
 * Players of Onimusha III will probably figure out quite easily, if not from the hundreds of other giveaways, who exactly Tenkai in Onimusha: Dawn of Dreams is.
 * In Super Robot Wars Original Generation 2 a certain character from the first game reappears in disguise. While Ratsel Feinschmecker's identity is immediately apparent anyway, the audience is left without any doubt whatsoever when Elzam Branstein's extremely distinctive (and insistent) Leitmotif starts playing.
 * Sin Episodes: Emergence, an otherwise mediocre sequel to a great game, does this very nicely by using variants on the characters' themes just before they appear. It's used to particularly good effect with Elexis.
 * In the video game Flower, Sun and Rain the end credits roll to a song nicknamed Welcome Home. That song may be the single most leitmotif-heavy song Masafumi Takada has ever written. One interesting thing about it is near the end of the song, it stops abruptly with a needle drop noise, and then resumes again. But when it resumes, you can actually catch the subtle leitmotif of the song Kusabi from Grasshopper's previous game The Silver Case. This is foreshadowing Flower, Sun, and Rain's stinger, which reveals that
 * In Mother 3, while breaking into the playroom of the enigmatic "King P", Lucas and party encounters a jukebox that plays.
 * The Magypsy theme music is a faux-Baroque string aria, but most of the time it's overlaid with kind of a funky saxophone countermelody. When appear, the former, . It's later revealed that.
 * Done waaay before that in Earthbound the enemy music in the final area of the game is a remix of  theme when you talk to him. Gee, wonder who the boss of that area is? Granted, it isn't his battle theme but it still is a spoiler/foreshadowing. Although, most people don't notice this, as   theme doesn't play often and it is one of the mroe forgettable tracks.
 * In Final Fantasy VII Advent Children, upon Kadaj, Loz and Yazoo's first appearance, before any other information is revealed about them, Sephiroth's leitmotif, 'Those Chosen By The Planet', plays in the background. This, of course, spoils Sephiroth's resurrection and the nature of his Remnants.
 * It takes a sharp ear, but in Super Paper Mario, the true identity of Count Bleck can be determined pretty early on if you notice that his theme is a variation on the "Memory" theme used during the flashbacks in-between chapters.
 * In Sonic and the Black Knight, the main theme is full of what seems like a bunch of knightly nonsense to fit the theme of the game, such as "I will conquer near and far" and "By the table I command." It sounds like it's about King Arthur, but it's performed by Crush 40, the typical "voice" of Sonic and Shadow. It seems like they just got lazy, until the end of the game reveals that . A few astute fans actually suggested something to this effect before the game was released based on the first verse of the song.
 * This get quite obvious when  before and after the duel against Percival.
 * In Kingdom Hearts Birth By Sleep, Vanitas's battle theme.
 * In addition, the Unversed boss themes.
 * Nomura has stated that Mysterious Figure's battle theme is also this. . Make of that what you will.
 * In Final Fantasy VI, Celes' theme is very obviously a variation on "Aria de Mezzo Caraterre", the song used for the famous opera sequence. It heavily foreshadows her Character Development in the second half of the game during the World of Ruin.
 * "Dancing Mad" is a massive Boss Remix of many different songs used in the game, and many of the pieces incorporated into it have some sort of symbolism attached if you listen hard enough.
 * In Digital Devil Saga 2 as soon as Inherent Will starts playing you know.
 * In Katawa Shoujo, this is combined with Chekhov's Gun in ending..

Web Comics

 * Listening to the Squiddles! album that was released as Homestuck merchandise tells you that something isn't quite right about the fictional show. So when Let the Squiddles Sleep played while Jade was trying to dream, the more devoted fans knew that something was going to go wrong.
 * Album listeners will instantly know what will happen in Intermission 2 when the music starts playing.

Web Original

 * It's hard to be sure this early, but the theme song to RWBY, "This Will Be The Day", definitely seems to be hinting at something.
 * The songs from the four Trailers also are clearly implying things; as of the first season's halfway point, "From Shadows" (from the "Black" trailer) seems to be the most comprehensible, referring (in retrospect) to Blake's history.

Western Animation

 * Absolutely expertly used in the Batman: The Animated Series episode "Perchance to Dream", where careful listeners get to notice the theme tune of the villain behind that episode's plot minutes before the reveal.
 * For the curious, the theme of  can be found here, while the theme of that episode's villain can be found here.
 * On Gargoyles, a rather surprising scene in "The Gathering, Part 1" reveals that Owen expected Oberon's attack and planned defenses, but would not stay around to help Xanatos in the battle. Just before he leaves, a certain leitmotif hints at the next episode's twist:
 * In Bruno Bozzetto's "Dancing", the ominous groaning music causes the dancer to look around warily, followed by the Grim Reaper showing up.