Please don't list this on a work's page as a trope. Examples can go on the work's YMMV tab.
Tear Jerker: Hogfather
The scene where the reader realises just why Death is enjoying pretending to be the Hogfather, and how sad he is that he can't do it forever. The tiny little Ho. Ho. Ho. caused me to break down completely.
When Death decides to screw Narrative Convention and utterly subvert the Little Match Girl story, despite Albert's objections.
The Hogfather can. The Hogfather gives presents. There's no better present than a future.
The Tooth Fairy, or the first Boogeyman. He was the absolute epitome of everything that goes bump in the night, yet he grew so attached to the children he was created to frighten that he saw all the terrible and real things in the world. His reaction? To protect children. He dedicates everything that he is and ever will be to creating a safeguard against the things that children truly ought to be scared of, but never should be. In his words...
Tooth Fairy: If you leave all those teeth around, anything could happen...you don't die here. You just get old, listening to the laughter.
As a frame of reference, he must be ancient. His final action was mustering enough power to literally frighten two hardened Thieves and a renegade wizard to death. He was intended to subsist on fear, but he managed to last for as long as the Tooth Fairy had been legend.