This is based on opinion. Please don't list it on a work's trope example list.
Tear Jerker / Whatever Happened to the Caped Crusader?
The way Clayface's expression becomes sorrowful when recalling how Batman sacrificed his life to save him. Being made of moldable clay, his entire face slumps, when recalling Batman told him everyone deserved to be saved. You can tell the entire episode rocked him to his core.
Bruce's mother telling him that the only reward he gets for being Batman, is to be Batman again, and worse, he only gets to have a few years of happiness.
Selina's version has her betray Bruce. When Batman comes to her for help, having already lost a lot of blood, Selina ties him up and lets him bleed out completely. As he does, she explains it as a Mercy Kill since she can't stand watching him destroy himself. One of the few times Catwoman is shown to kill, and it's Batman.
Superman's story of Batman's death, and that he knew it was suicide, but if it saved one person...
The Riddler's lamentations from the Bonus story in the TPB "When is a Door." A TV crew is trying to interview criminals, and they find an old Riddler who takes care of a "junk yard" which is comprised of many wondrous attractions past their time. They represent his own state, and the nostalgia he still holds onto.note The speech is also a lamentation of fans who grew up watching the 1960's Batman show.
Reporter: "So tell us, what's the most impressive crime you've ever committed?"
Riddler: "I robbed a bank underwater, once. The clue for that was left on a giant crossword puzzle on the side of the cross cleaning company building. They tore it down, years ago, I think it's in here somewhere. None of this stuff works any more. They're all rusted up and forgotten. You know what they call them now? Camp, Kitsch, Corny... Dumb... ...Stupid. Well, I loved them — they were part of my childhood. Back then, they all worked perfectly, the guns fired, the cameras took pictures, the pencils wrote. Nobody comes down here anymore. ...Nobody but me.