For a cute, saccharine show, My Little Pony: Friendship Is Magic has a lot of villains that cross the line, proving that even though Equestria is all about instant forgiveness there are still some things that are considered unforgivable.
- "The Crystal Empire Part 1" does this to King Sombra immediately upon his introduction where it's revealed he turned the Crystal Empire into Mordor and enslave the crystal ponies who lived there. Notably he lack any explanation or mitigating factors unlike prior major villainsexplanation and is portrayed more as a monstrous force of evil than an actual character.
- In "Twilight's Kingdom Part 2", Lord Tirek crossed this by having Discord betray and imprison Twilight's friends only to similarly betray Discord and drain his magic. Discord remained sympathetic even before being betrayed as he had moments of conflictedness about it and only did so because he thought Tirek was a more compatible friend, while Tirek betrayed and rejected the friendship that redeemed Discord.
- The griffin guide in "The Lost Treasure of Griffonstone" crosses it by abandoning an injured Rainbow Dash in a abyss just because Rainbow didn't have enough bits.
- Queen Chrysalis was shockingly evil upon her debut in "A Canterlot Wedding", but crosses to irredeemably in "To Where and Back Again Part 2" when she attacked Starlight Glimmer and attempted to drain Thorax's love when they challenged her rule by the latter having discovered a cure to their Horror Hunger, invalidating her prior mitigating motivation of feeding her subjects. This, followed with her refusing the offer of redemption for the good of her subjects, established her as a pure tyrant irredeemable even by what had become a notoriously forgiving series.
- In My Little Pony: The Movie (2017), The Storm King crosses the line by creating a massive tornado that threatened to destroy Canterlot along with his own army, then backstabbing and attempting to murder Tempest when she asks for him to fix her horn to fulfill his end of the deal.
- In School Raze Part 1, Cozy Glow crosses it once it's revealed she tricked the Mane Six into imprisoning themselves in Tartarus to take over the School of Friendship and was behind stealing all of Equestria's magic to banish to another dimension (alongside Starlight Glimmer whom she usurped) just to take power for herself. Her actions were so horrific that she ended up in Tartarus with Tirek as punishment.
