This is based on opinion. Please don't list it on a work's trope example list.
Tear Jerker / Fushigi Yuugi
A lot of lovable characters may have died in Fushigi Yuugi but none of them hold a candle to the death and eventual spiritual reunion of Star-Crossed Lovers Tatara and Suzuno. Can people say "greatest love story ever"?
For a non-death example, there is Hotohori's doomed confession of love to Miaka matched to a flashback showing his lifelong fascination with the Priestess of Suzaku.
When Tamahome realizes his eleven-year-old brother had attempted to protect the family from Suboshi's attack with a kitchen knife, which of course was absolutely no match for Suboshi's Killer Yoyo. As if that part of the story wasn't sad enough.
Not to mention that when Miaka talks to him while he's burying his family, he turns around and is shown with about six lines of tears pouring out of his eyes.
And what about when Tamahome is cradling his youngest and dearest sister in her final moments?
Basically, the entire event of Tamahome's family being slaughtered by Suboshi is sure to turn the waterworks on.
What makes it even worse is that there was absolutely no warning whatsoever that this was going to happen. Tamahome just spends a bit of time shopping for them, opens the door with a happy, expectant look on his face...only to find that they're all dead. No foreshadowing, no way for us to have seen that this was what Suboshi had in mind. Also made worse by the fact that none of the neighbours did anything to help (out of fear for their own lives, mind you), and the Fridge Horror that if Tamahome hadn't gotten there when he did, then the bodies might not have been discovered until much later...
Amazingly, even though he's way over the Moral Event Horizon by this point in the story, Suboshi also commits one of the most poignant sacrifices in the series: giving his brother a memory-erasing drug to spare him the bloody life of a Seiryuu warrior. Given that Amiboshi is Suboshi's entire family, that Suboshi had previously been nearly insane with grief when he thought Amiboshi to be dead and then used this as his Freudian Excuse for the Moral Event Horizon crossing... when he watches Amiboshi resume his peaceful life as "Kaika" and says goodbye forever, it's hard not to reach for the hankies.
The Suzaku and Seiryuu warriors' trip to the hot spring omake ends with a glimpse of the Animated Actors going out for a drink. Miaka takes one last look at the recording as if saying goodbye to the viewers who were watching the show.
Suzaku Hi Den not only gives the spotlight to Hotohori, but to his wife Houki and his half-brother Shu Tendou. It's absolutely heartbreaking, specially when Houki tries to stop Shu from killing Hotohori and then when he dies in both Houki's and Hoto's arms.
Though YMMV, a lot of the scenes involving what happened to Yui can be this. By the time the series ends, every single aspect of her life has been crushed, including her humanity. She gets better, but, even so...