''Naughty Marietta'' is an operetta with music by Victor Herbert and libretto by Rida Johnson Young. It opened in October 1910 in Syracuse, New York, and was the TropeCodifier for American operettas.

The story is set in 1780 New Orleans, and focuses on American Captain Dick Warrington's attempt to capture the notorious pirate Bras Pique, as well as his developing relationship with the beautiful and spirited Neapolitan Countess Marietta D'Altena, who's come to New Orleans as a casquette girl to escape an ArrangedMarriage and to find the man who can complete her DreamMelody, as that's who it's foretold she'll marry. There's also romantic tension between Lizette, another casquette girl, and Silas, Captain Dick's and later French Lieutenant-Governor Grandet's servant (called Simon in the original premiere, then changed to Silas in other versions).

In 1935 ''Naughty Marietta'' was loosely adapted into a film directed by Robert Z. Leonard, starring Jeanette [=MacDonald=] as Marietta and Nelson Eddy as Warrington. It was the first of [[ThoseTwoActors eight musical films]] that co-starred [=MacDonald=] and Eddy. The film took many liberties with the plot of the operetta, including changing Marietta into a French princess named Marie, and eliminating the characters of Lizette, Simon/Silas, and Etienne in order to concentrate on the Marie-Warrington romance. Forty years later, [=MacDonald=]'s performance of "Ah! Sweet Mystery of Life" was memorably sampled in ''Film/YoungFrankenstein''.

!! This work contains examples of the following tropes:
* ArrangedMarriage: Marietta ran away to escape one in Naples.
* BetaCouple: Lizette and Silas/Simon.
* BeautifulSlaveGirl: Adah, Etienne Grandet (Lieutenant-Governor's son)'s quadroon slave mistress.
-->'''Etienne:'''(''at Quadroon Ball, where he's auctioning her'') "La Belle Adah, the most beautiful slave in New Orleans!"
* TheBigEasy: New Orleans during its time as a French provincial town. Still fun.
* BilingualBonus: Doubles as a MeaningfulName. "Bras Pique" means "tattooed arm" in French. Etienne has "Bras Pique" tattooed- guess where? So do his pirate crew.
* BreakawayPopHit: 'Ah! Sweet Mystery of Life', the DreamMelody, is an older example, since ''Naughty Marietta'' was written in 1910.
* CorruptPolitician: Lieutenant-Governor Grandet.[[spoiler: His son, Etienne, is Bras Pique. And he's one of the only two people who know. His family uses whipping boys to take punishments for them. Silas gets appointed as the new whipping-boy midway through the operetta.]]
* DevilInPlainSight: No-one except his father and his slave mistress Adah has ''the slightest clue'' that [[spoiler: Etienne is really Bras Pique or that he wants to establish Louisiana as an independent nation, a dictatorship under his control]]
* DreamMelody: 'Ah! Sweet Mystery of Life' is the TropeNamer.
* IAmSong:
** The title song, where Marietta sings about how "there are two little maidens that live in my heart" and "when I'm good I'm very very good, but when I'm bad I'm horrid!"
** Also 'Tramp, Tramp, Tramp!' which introduces Captain Warrington and his band of soldiers and woodsmen.
* IJustWantToBeFree: When Adah is freed at the climax, she [[spoiler: exposes Etienne's secret]]
-->'''Adah''': I- a free woman? Then.. I must act like one-- Listen, Monsieur, you would prevent this marriage? \\
'''Dick''': If I could. \\
'''Adah''': On Etienne Grandet's right arm you will find his name! \\
'''Dick''': His name? \\
'''Adah''': Bras Pique!
* InNameOnly: The 1935 movie, which removed the stage characters of Adah and Etienne, eliminating the hunt for Bras Pique, and making Marietta French, among other changes. But then, YMMV.
* IWantSong: 'Neath The Southern Moon' for Adah, after she discovers that [[spoiler:Etienne has stopped loving her. He's paying attention to Marietta in the hope of getting her to marry him.]]
* KickTheDog: Marietta considers Etienne to be doing this when he tells her that he plans to sell Adah, who is genuinely in love with him.
* LampshadeHanging: On the poor quality of Marietta's disguise as a boy.
* MistakenForCheating: A variation- they weren't really a couple yet, but Marietta decides to accept Etienne's proposal when she thought Warrington was flirting with Adah.
* MixedAncestry: Adah.
* OfficialCouple: Warrington and Marietta.
* RealLifeWritesThePlot: Emma Trentini, the original Marietta, was an Italian opera diva with a heavy accent.
* RebelliousPrincess: Marietta is a non-royal version. (In the movie she is in fact a royal French princess.)
* RunawayFiance: Guess who?
* SlaveLiberation: At the Quadroon Ball, Warrington buys Adah to set her free.
* SweetPollyOliver: Marietta disguises herself as a boy to remain hidden from people looking for the Countess. Her disguise isn't very good.
* TheIngenue: Coloratura soprano Marietta.
* VillainSong: 'You Marry A Marionette', sung by Etienne trying to convince Marietta to marry him.

!!Tropes in the 1935 film:

* DressingAsTheEnemy: How Marie is eventually liberated from the governor's mansion. Two of Warrington's men, dressed as the governor's men, smuggle them out.
* GettingCrapPastTheRadar: Marie, scrambling to avoid getting forced into a casquette girl marriage, obliquely tells the governor that she used to be a prostitute.
--> '''Marie''': Surely you have room in New Orleans for a girl who doesn't want to become a housewife, who likes to be charming and pleasant?"
* HaveAGayOldTime: "People are rather gay ni this quarter of town."
* IncrediblyLongNote: Eddy holds a note so long that all the music stops and all the other characters gawk at him.
* IndenturedServitude: Sort of. Casquette girls (and this was a thing that happened in RealLife) were sent to Louisiana all expenses paid in the expectation they would marry a French colonial. If they didn't, they were supposed to go back to France.
* KingIncognito: Marie assumes the identity of a servant girl named Marietta in order to escape from Paris and her ArrangedMarriage.
* {{Pirates}}: The "Brutes" variety, as they coldbloodedly murder a casquette girl and seem to be getting geared up to rape the others when Warrington's men show up and annilhilate them.
* PragmaticAdaptation: As noted above, Marie gets changed from French to Spanish and the BetaCouple plot is dispensed with. The character of Adah is gone. The character of Etienne is also eliminated, as accordingly is the reveal that he's the pirate. The pirate plot is still there but is greatly reduced in importance. The pirates are only in a couple of scenes in which they kidnap the casquette girls only to be promptly defeated by Warrington's men.
* RedLightDistrict: Where Marie winds up in New Orleans, in the house belonging to a real courtesan who apparently had to make a hurried escape from the city.
* VerbalIrony: When Warrington picks up on something in the bearing of Marietta the casquette girl and calls her "Your Highness."