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->''If there ever was a time, if there ever was a chance''
->''To undo these things I've done, and wash these bloodstains from my hands''
->''It has passed and been forgotten; these are the paths that we must take''
->'''Cause you and I, Tom, we are men, and we can bend and we can break''
-->--'''Dr. Wily''', "[[Music/TheProtomen The Hounds]]"
* The Billy Bragg song ''[[http://www.youtube.com/watch?v=ojPTz4VAOMA Never Cross a Picket Line]]'' argues that...well, [[CaptainObvious crossing picket lines]] is a moral event horizon. It was written to support the three-year long, and ultimately successful Liverpool Dockers' Strike of 1995-8.
-->''Two years gone by but still they never,''
-->''Ever cross a picket line.''
-->''With their wives and children they stand together.''
-->''Never cross a picket line!''
-->''You must never cross a [[http://en.wikipedia.org/wiki/Picketing_(protest) picket line]]!''
* [[Music/CoheedandCambria Amory Wars']] BigBad, Wilhelm Ryan, and [[TheDragon Dragon]], Mayo Deftinwolf, crossed this right off the bat. Ryan orders the titular characters' children killed because one ''might'' grow up to be TheChosenOne. Mayo gleefully [[ManipulativeBastard manipulates]] Coheed into doing the deed, making him believe his children are going to go AxeCrazy and destroy the universe because of a (nonexistent) virus. And all of this transpires in the ''second song'' on the first album. [[SelfFulfillingProphecy One survives]], and grows up to be a rather dark and cynical MessianicArchetype.
** Coheed's event horizon would likely be either when he uses a very painful virus/poison/whatever provided by Mayo to kill his youngest children, toddler twins Matthew and Maria. Right after telling them that [[BlatantLies everything will be all right,]] or [[MyGodWhatHaveIDone after he realizes how horrible that must have been]] and decides to kill his next child (his twenty-something, recently engaged and [[RapeAsDrama raped]] daughter) with a ''sledgehammer.'' And this is one of the ''[[WhatTheHellHero protagonists.]]''
* In The Rake's Song by Music/TheDecemberists, the titular character sings of how he married young and left his licentious life behind, only to come to regret it round about the time his wife had their first child. When she dies in childbirth and he gets stuck with the remaining kids, he decides that getting his old life back is a simple matter of OffingTheOffspring. He happily explains how he did his three children in, and then gloats that the listener would expect him to be haunted with guilt from these acts, but really [[KarmaHoudini he's not that bothered]]. In the proceeding songs, he [[spoiler:kidnaps and rapes Margaret]], with the help of the Forest Queen. He gets his comeuppance in the end [[UndeadChild though]].
** Then the Forest Queen herself crosses over when she [[spoiler:flies The Rake across an uncrossable river after said abduction of Margaret, so that her adopted son would never leave her for Margaret.]]
*** Especially [[spoiler:when she's sworn an oath to her son that he can have one night with his love before he has to come back to her forever anyway]].
* Another Decemberists example is "The Culling of The Fold", in which the narrator encourages others to engage in their own Moral Event Horizons such as torturing and murdering their closest friends and lovers. It's possibly a companion to the song "Shankhill Butchers" which Meloy specifically said that was about the '' story '' of the Shankhill Butchers. Their story was told to children to frighten them into behaving.
* Edward Baynes in Music/DreamTheater's ''Metropolis, Pt. 2: Scenes from a Memory'' crossed this line when he [[spoiler: shot and killed his brother Julian and said brother's lover, Victoria, and [[KarmaHoudini got away with it]]]]. And just when you thought it was over, [[spoiler: the Hypnotherapist, implied to be his reincarnation, kills Nicholas, Victoria's reincarnation. Like he couldn't resist killing someone once...]]
* Music/{{Eminem}}'s song "3 AM" deals with how a serial killer's mind works (a la the characters in slasher films, which he portrays in the song). In the final verse, he explains when he crosses the threshold by explaining when his "days of serial murder manslaughter begun". He describes when he dismembered his cousin, cutting him up and drinking his bath water (when he first thought about drinking the murdered's blood instead).
* "Dance with the Devil" by rapper Music/ImmortalTechnique. It tells the story of a fatherless teenage boy in the projects seduced by greed into a life of crime. The climax is his gang initiation, in which he has to "rape a bitch to prove he was real." [[spoiler: Except he ended up [[ParentalIncest raping his own mother]]. [[MyGodWhatHaveIDone He was horrified by what he's done]] and killed himself. He's said to have "died [[TheSoulless with no soul."]]]]
--> "I'm falling and I can't turn back. I'm falling and I can't turn back."
** The more obviously titled Immortal Technique song: "Point of No Return" It is about this trope and nothing else.
* The narrator of Music/ViolentFemmes' "Country Death Song" belatedly realises that he crossed the MoralEventHorizon when he [[spoiler: threw his youngest daughter into a well]]:
--> I'm goin' out to the barn with that never-stoppin' pain
--> I'm goin' out to the barn to hang myself in shame...
* As for gangsta rappers UpToEleven such as Music/EazyE, Music/TheNotoriousBIG, Music/GetoBoys, Music/{{Gravediggaz}} or Music/{{Esham}}, this is practically a recurring theme for almost any song of theirs.
* GWAR (and sometimes their enemies) do this ALL the time.
* There are more than a few of these in operas as well. Sometimes the major villain (or AntiHero) has to do something really bad, otherwise people might still sympathise with him.
** At the start of Music/WolfgangAmadeusMozart's "Don Giovanni", the title character - already portrayed as somewhere between a MagnificentBastard and AffablyEvil - first tries (and fails) to rape Donna Anna offstage, then murders her father onstage while trying to escape after she's fought him off. Later on, he shows his AffablyEvil side by trying to seduce the village girl Zerlina - on the day before her planned wedding, no less. This actually fails when his ex-lover (or ex-wife, if you believe her claim) shows up. He throws a party at his home, invites the whole village as a distraction, drags the girl offstage and has his wicked way with her. And that's just Act 1... in Act 2, whilst still on the run, he manages to humiliate the ex-lover by setting her up with his servant disguised as himself beat up Zerlina's husband-to-be: and, off-stage, seduce the wife of his own loyal servant Leporello. And brag to Leporello onstage about it afterwards. And then, mockingly, invite the statue of the man he murdered, to come to dinner. Unfortunately, that didn't end well for him... but the statue gives him a chance to repent of his evil ways, and Don Giovanni *refuses*. He knows perfectly well he's crossed the Moral Event Horizon - he's talking to the statue of the man he killed when he did it.
** In Bizet's "Carmen", Don Jose actually LOST the real reason for his moment of Moral Event Horizon Crossing in the opera, as compared to the original novel that the opera was based on. In the book, he actually kills his commanding officer, in the fight over the eponymous Carmen: at the corresponding point in the opera, the fight is broken up by Carmen's smuggler friends (who arrived too late in the book), and Officer Zuniga is still alive when dragged offstage by them. (His fate would seem uncertain, except he has one line in a crowd scene an hour later to reassure us he is still alive - although the line could equally well be sung by his deputy, Sergeant Morales.) Nevertheless, Jose decides he has no choice but to join the bandits (rather than remain behind and face the music from his still-alive officer.) Part of Act 3 of the opera revolves around references to his aging, sick mother (off-stage), the only person left who believes he might be redeemable... He ends the opera by murdering Carmen and turning himself in to the guards. But it's kind of less clear when he crossed the MEH although he certainly did at some point.
** In Beethoven's "Fidelio", the corrupt governor Pizzaro is already pretty evil - imprisoning political enemies after show trials, and in one case no trial at all. But his Moral Event Horizon could be ordering the murder of Florestan, in the prison, to prevent Florestan (the one who never got a trial, and had evidence of Pizzaro's corruption) being found or freed by the new Minister of Justice. His jailer, Rocco, is offered the chance to cross the Moral Event Horizon himself (by doing the murder), for money, but refuses - it is not clear whether out of cowardice or principle - and agrees only to dig the grave and let his boss do his own dirty work. Rocco even later does a HeelFaceTurn, at a point where he technically could have got away with backing his boss (by picking up the pistol dropped by "Fidelio" and pointing it at Pizzaro instead of handing it to him, just before the Minister arrives for the prison inspection. To his credit he doesn't even seem to realise that there was an alternative option.)
** Wagner's "Ring" cycle has one Moral Event Horizon after another. Alberich crosses it at the start by stealing the Rhinemaidens' gold: Wotan and the gods cross it by stealing it (and the eponymous ring) off him purely because they need to pay off a debt: Fafner, the giant they pay off, kills his brother to keep all the treasure. Siegmund, the one who should have been the gods' DesignatedHero, crosses it by committing incest with his sister, and thus must die against Hunding rather than being allowed to defeat him: Brunnhilde crosses it herself by disobeying Wotan's orders and protecting Siegmund, and as a punishment is stripped of her status as a Valkyrie and forced to become mortal. Even Siegfried is tricked into it by betraying Brunnhilde and not only marrying Gutrune but forcing Brunnhilde to marry Gunther. It's repeatedly made clear that there's no way back for any of them, although Brunnhilde is the only one to actually realise the situation, seize the moment and turn it into a case of RedemptionEqualsDeath, by throwing the Ring back into the Rhine, to its only rightful owners the Rhinemaidens (thus breaking its curse), and immolating herself on Siegfried's funeral pyre.
* [[Music/{{Gorillaz}} Murdoc]] finally crossed it when he kidnapped and imprisoned 2D. It wouldn't be quite so bad if not for all the [[FridgeHorror horrific undertones]] of the drugging, incarceration and physical abuse. Granted, 2D was never the bravest or keenest individual, but he was always pretty harmless. Murdoc's brutality and the constant isolation have all but [[BreakTheCutie broken]] the singer, and it's around that point that Murdoc bridged the MoralEventHorizon.
* In the "Servant of Pain" portion of the Fireaxe epic ''Music/FoodForTheGods'', we're introduced to a band of WellIntentionedExtremist revolutionaries fighting to free their land from TheEmpire, and they at first seem quite heroic, leading a furious assault upon the Citadel. But when they actually breach the Citadel, things get horrific in short order in "Cut or Be Cut" and "Atrocity", which showcase just how [[TheRevolutionWillNotBeCivilized uncivilized this revolution actually is]]. People are slaughtered left and right, the priests are flayed alive and left for the rats, and when they get to the royal family, all but one of the sons are slaughtered, the daughters and their mother are raped and killed, and the sole surviving son, who is [[ForcedToWatch made to watch all of this]], is then coaxed into murdering his royal father. And ''then'' we learn that the leader of the revolutionaries did all of this to further subjugate the populace under divine tyranny, by subjecting them to so much fear and horror at this atrocity that they'll follow their god's every dictate in the name of "never again".