* ''{{Urinetown}}'' ends with the heroes triumphantly toppling the [[CorruptCorporateExecutive evil toilet monopoly]] and launching a new era of free urination. Only, as it turns out, the monopoly was right about the water shortage, the newly unrestricted flushing makes the town run dry, and everyone dies of thirst.
-->'''Little Sally''': What kind of a musical is this?! The good guys finally take over and then everything starts falling apart?!\\
'''Lockstock''': Like I said, Little Sally, this isn't a happy musical.\\
'''Little Sally''': [[SoundtrackDissonance But the music's so happy!]]\\
'''Lockstock''': Yes, Little Sally. Yes, it is.
** [[https://en.wikipedia.org/wiki/Thomas_Robert_Malthus Hail Malthus!]]
* ''[[Creator/HenrikIbsen The Wild Duck]]'' Nice job telling your friend his family's been lying to him all these years. [[spoiler: And now his daughter's dead]].
* ''Theatre/{{Wicked}}'' finds Elphaba listing her contributions to this trope in the song "No Good Deed".
* ''Theatre/SweeneyToddTheDemonBarberOfFleetStreet'': If Anthony Hope didn't bust in Sweeney's barber shop in the midst of his shaving of Judge Turpin, his plans to rescue Johanna Barker would have gone according to plan, and Sweeney himself wouldn't have gone off the deep end due to being denied his first shot at revenge.
* In ''Theatre/PokemonLive'', Pikachu's Thundershock and Thunder were the last two moves [=MechaMew2=] needed to learn; with the list complete, nothing can stop Giovanni from conquering the world.
* In ''Die Entführung aus dem Serail'', the first really German opera by Music/WolfgangAmadeusMozart, one can only pity Belmonte. [[spoiler: When he's captured along with his bride, he says his father's rich and can give a generous ransom. Only to find out that his father is their captor's bitterest enemy. And for the lady, whose faithfulness, incidentally, Belmonte [[GreenEyedMonster highly doubts]], to learn of her bridegroom's doubtful heredity.]]