Some of the examples that follow also fall under one or more Death Tropes. Most spoilers will be unmarked ahead. Beware.
Cynicism Catalysts in Western Animation.
- In the American Dad! episode "Hayley Smith, Seal Team Six", it's revealed that Hayley used to be happy and carefree until her seventh birthday when she saw a news report of a baby seal being clubbed to death, which made her realize that life wasn't fair and turned her into the grumpy Soapbox Sadie she is today.
- When Scarface murdered Dreamer, the youngest daughter of Fox and Vixen, in The Animals of Farthing Wood, this led not just to the feud between the red and blue foxes, but also resulted in Bold, their eldest, attempting to hunt him down when he got old enough.
- In Avatar: The Last Airbender, Iroh and his son Lu Ten could be considered an inversion (similar to Dumbledore and Ariana). Iroh was one of the Fire Nation's most feared generals until Lu Ten died in his legendary siege of Ba Sing Se, at which point Iroh abandoned the siege and had his experience in the spirit world. By the time the show actually starts, he puts the "cool" in Cool Old Guy, is the grandmaster of a secret, international society of fellow awesome old people, and is clearly only sticking with the Fire Nation army so he can give his nephew Zuko an alternate role model to Ozai.
- Batman: The Brave and the Bold has Aquaman spend an episode depressed after he fails to save a whale from poachers. Fortunately he's able to buck up by the end and help Adam Strange out of his own Despair Event Horizon.
- Darkwing Duck: An alternate timeline in "Time and Punishment" showed Darkwing Jumping Off the Slippery Slope as the "crime fighter" Darkwarrior Duck when Gosalyn disappeared.
- In Justice League "A Better World", the Justice Lords are revealed to have started falling off the slippery slope after their Flash was murdered.
- Legion of Super Heroes (2006) has Ayla, aka Lightning Lass: instead of gaining awesome lightning powers when her brothers Garth and Mekt do like she did in the comics, she's vaporized, pushing the brothers into their guilt-driven Cain and Abel complex. Ultimately Mekt makes a Heel–Face Turn when she turns up Not Quite Dead.
- My Little Pony: Friendship Is Magic:
- In the first episode, before learning The Power of Friendship, Twilight blew off her friend Moondancer's party to go and study. In Season 5, Twilight decides to try and make amends with her old friends but finds that to Moondancer, who was very shy, the fact that Twilight (with whom she had the most in common) didn't show was a real blow to her self esteem.
Moondancer: I gave Friendship a chance a long time ago. It didn't work out then; it isn't gonna work out now.- In the Season 5 finale, we learn that Starlight Glimmer's turn to anti-Cutie Mark extremism occurred when her best friend, Sunburst, was sent away to Celestia's School for Gifted Unicorns after earning his mark.
- In the movie, Tempest Shadow's backstory during her Villain Song "Open Up Your Eyes" shows that she became alienated from her friends following an encounter with an Ursa Minor that broke her horn and scarred her face, which lead to her striking a Faustian deal with the Storm King in the hopes of getting her horn restored.
- Throughout Rick and Morty, it is hinted that Rick Sanchez became what he is as a result of an experience that occurred in his past. It's finally revealed in the season five finale that his supposed fake backstory from "The Rickshank Redemption" in which his wife and daughter were killed by an alternate Rick was real and afterwards, he went on a Roaring Rampage of Revenge throughout the multiverse, but was never able to find his family's killer, that failure sending him into a drunken spiral of despair and cynicism.Tony: You know what shy pooping is, Rick? It's a pointless bid for control. You want to take the one part of life that you truly think is yours and protect it from a universe that takes whatever it wants. It took my wife, it clearly took something from you. We can spend our lives fighting that, or we can choose to be free.
- In Robotech: The Shadow Chronicles, Marcus Rush is hurt by the death of his older sister, (original) Marlene who was killed by the Invid at beginning of Mospeada, which is the reason he hates Invids so much. This results in quite a few rage attacks.
- Shadow Raiders. Graveheart's younger brother perished in a raid Graveheart was leading against Planet Fire for energy; this explicitly caused him to renounce his position in the elite Quarriors and become a simple miner instead and is implied to be the reason why he is so keen on the idea of peaceful trading replacing the former raid-based interactions between the worlds.
- Spider Man Across The Spiderverse: Miguel O'Hara was never a particularly rosy person, but he became all the more cynical and cold when he learned firsthand what happens when you try to alter a "canon event": after discovering an alternate dimension in which his counterpart died but his family survived, Miguel tried transplanting himself into the alternate dimension, taking his counterpart's place and leading a happy life as a loving father. Unfortunately, in so doing, he destabilized the dimension to the point that everyone in it, including his daughter, ceased to exist. Emotionally broken from this trauma, he redoubled his efforts to preserve the integrity of the multiverse by ensuring nothing interferes with the "canon events", traumatic though they may be, and thus bringing him into conflict with Miles, who is still idealistic enough to think he can prevent his own "canon event" by saving his father, but in so doing risk destroying the multiverse.
- Star Trek: Lower Decks: Mariner is someone who truly believes in Starfleet's mission as a science and exploration organization and was considered a safe bet for first in her graduating class to make captain rank. But the death of her friend Sito Jaxa (followed several years later by the horrors of the Dominion War) stomped out any idealism she may have had and left only a reckless jerkass who actively sabotages any potential promotions because she doesn't want the responsibility of deciding who lives and who dies.
- In Star Wars Rebels, the death of Mira and Ephraim in addition to the stress of increasing stakes took subtle effects on Ezra Bridger, with Ahsoka's supposed death and Kanan's blindness thanks to him trusting Maul being the final straw for Season 2. By the beginning of the next season, we see him commit more questionable acts such as Psychic-Assisted Suicide and lifting his Thou Shalt Not Kill ideals.
- In Steven Universe, despite The Diamonds status as a Dysfunctional Family, they still care for each other. Pink Diamond's death drove Yellow Diamond and Blue Diamond to grieve for her for countless centuries.