Bittersweet Candy Bowl, Lucy when she thought Mike died and shortly after, when she finally confessed her love for him and he rejected her. The first one came with Dissonant Laughter. Chapter 63 is getting sadder and Lucy looks about at the horizon here.She was okay, then Mike ignored her existence. Now...
Trudy crosses this in General Protection Fault after seeing Nick, (whom she had loved) propose to Ki, which Ki accepts. She had been starting to regret her actions, but this pushes her even further, and she attempts suicide in the next arc in which she appears.
Very nearly everyone with a speaking part in Gone with the Blastwave, though it doesn't manifest in quite the usual way. Rather than some grand gesture like falling into an Angst Coma or being Driven to Suicidenote apart from that one guy from the Blue army who Ate His Gun, they've all just become desensitized to the constant bloodshed and are operating on some sort of Heroic Safe Mode.
Eridan crosses both this and the Moral Event Horizon in the same scene. He gives up any hope of beating Jack and defects to his side, killing off his unrequited love interest AND his species' only hope for revival in the process. This makes his Sgrub title, Prince of Hope, rather prophetic- it was later explained that "Prince" roughly translates to "Destroyer."
Later, Roxy crosses it too after a disastrous turn of events leaves nearly all of her friends dead and Rose, the alternate version of her mother who she had barely met, died in her arms. She later confesses to John that she thinks it would be better if they gave up so that they could be with their friends in the afterlife.
In Keychain of Creation, an Exalted webcomic, this is canonically how Abyssal Exalted get created, as shown in Renegade Deathknight Secret's backstory flashback. Her entire village is killed by a demonic plague, she's deathly ill, and just as she's given up all hope of living, the Neverborn show up and offers her Exaltation in exchange for servitude.
Jadis saw the True Shape of the Universe and became The Omniscient. Upon seeing the Universe is essentially 99% emptiness, both across time and space, the relatively little amount of 'existence' that floats in the middle of all the nothing made Jadis go completely mad and lose all hope, drive and self-initiative. She's currently slowly rotting inside a crystal that keeps her alive, tormented by her perfect knowledge of the universe and wanting to die despite knowing perfectly when and if it happens and everything that happens after she's dead.
The whole point of Servant Chaos's actions in Sailor Moon Cosmos Arc was to force Usagi to this point to get her willing to merge with Chaos. Having her daughter and husband brainwashed, forced to fight them, accidentally killing the Asteroid Senshi, realizing that everlasting peace is impossible and learning that this is all her fault for unconsciously wishing Chibiusa never woke as a senshi did the trick, eventually getting her to perform a Suicide by Cop.
Anna Enfield's from Sire lead a fairly troubled life which took a sharp turn when the sister that she shared a body with used it to murder their beloved uncle. Having seen herself kill someone she loved and knowing that her Hyde half could not do that unless she desired it, Anna turns a knife on herself and tries to commit suicide.
Skin Horse: Tip hits this in the aftermath of the "Sure as Your Born" storyline: Normally a metrosexual Wholesome CrossdresserLovable Sex Maniac, he literally traded his entire wardrobe for the ultimate male power suit, in order to speak in favor of a nonhuman rights bill (without his crossdressing becoming the focus). Not only does the bill fail to pass, but in the immediate aftermath the entire world seemed to come down with some sort of Weirdness Censornote Whereas a few people seemed to be incapable of seeing Sweetheart and other transgenics and cryptids as they were, now it seems only a few people can actually see what's really going on. Which made for a doubly Senseless Sacrifice, causing Tip to spend the next couple of chapters wearing a Beard of Sorrow, a dirty t-shirt and boxers (having given his other clothes away). An attempt at Playing Cyrano for Sweetheart only ending up making things worse. (That and the giant lobster attack)
In Snarlbear Flint passes one near the end after losing his hometown, corrupting Daisy, and then losing Daisy's support as well, in the end being left with only money. as a result, he turns into a dragon
In Stand Still, Stay Silent the Battle of Kastrup was this for the Danish army. About ten years before the start of the story, they tried to retake part of the Forbidden Zone that used to be mainland Denmark only to have the entire force wiped out in a single night by one of the many threats roaming in the area. After this, they don't even send scouts there anymore.
Trapped: Chae-ah hits hers when her ex-boyfriend comes back into the picture and resumes stalking her, to the point she has a breakdown in the rain and makes a deal with Yunsu to get rid of him.
True Believers has Spider-Man lose his wife, his home, and his job at the Daily Bugle all in the first 11 pages. As a result, he asks Dr. Octopus to kill him. Unfortunately for him, Death Is Cheap in the Marvel Universe, so not even murder can end his suffering.
In Weak Hero, an escalating series of traumas causes Gerard to hit this in his backstory. An agency targets his band for a scam, causing Hyeonjin to quit. Gerard begs him to return, enamored as he is with Hyeonjin's music, only for Hyeonjin to reveal that he never liked the band or the music that Gerard cared for so much. Meanwhile, a bully at school gets so obsessed with Gerard that he beats Gerard's friend into a pulp and then sets their practice room on fire. Gerard leaps in to save Hyeonjin's music, only to get caught in an explosion that hospitalises and scars him. It's because of all of this that he completely loses the will to play the music that he once loved. Fortunately, a year later, he becomes a True Companion to Ben's gang and rediscovers his love of song.
Catt, one of the three protagonists of Wonderlab, ends up crossing this twice throughout the entire series.
In their backstory, when they catch a senior Agent they greatly admired beating another Agent out of insanity, they proceed to send up coming to the conclusion abandon their human side for the sake of survival in the facility (but not before attempting, and failing, to commit suicide via drowning themself in the water produced by the Bottle of Tears).
The second time was in Episode 48, after coming across the mummified corpse of their branch's Manager, who had taken their own life since their holographic assistant, Manual, was unable to reciprocate the Manager's love because of its nature as a machine. This leads Catt to believe that the human heart can't be strengthened or discarded, and that the heart was always doomed to wither. They proceed to undergo a Distortion shortly afterward.
She was okay, then Mike ignored her existence. Now...