Dungeons & Dragons; this is likely the best ending the Player Characters can hope for in the apocalyptic scenarios presented in the Elder Evils Splat book. The PCs may manage to defeat the beast and Save the World, but given how each Elder Evil comes with a Sign that causes global cataclysms, there may not be much of the world left at that point. (The book does say they are meant to be used as finales for long-running campaigns.) For example, Atropus causes a worldwide zombie plague that causes undead to outnumber the living at worst, the Hulks of Zoretha cause a Hate Plague that causes mortal beings to become enraged and fight each other, and Father Lymic freezes the world with endless night, destroying crops and wildlife and making any recovery a difficult task. What's more, two of them, Pandorym and Zargon, are not truly defeated, and the PCs must do something else to ensure that later.
Sort of an in-universe example in Yu-Gi-Oh! is the Trap Card Kozmourning, a card representing the end of the Kozmo story (seeing as its OCG name is "Kozmo Epilogue"). The scene shows Kozmo Farmgirl and Kozmo Goodwitch crying over the death of Kozmoll Dark Lady, a likely indication that, much like Star Wars (which the Kozmo archetype pays partial Homage to) the conflict ended with victory for the heroes, but at great cost.