Animal Cruelty is Just Wrong

When it comes to for a probably of having a psychopath in the making, animals are often among the first targets. However, that’s not the case in this trope, where even the Big Bad guy would be upset if an animal got hurt by another person that didn't deserve it. While allowing nature to take its course on harming animals is one thing, for many who fall under this trope… as far as they’re aware of, nature is the only allowed to hurt animals since they understand about survival. Many characters would often restrict their killings of animals to either put the creature out of its misery, for food only, and/or defense… some would refuse to hurt animals -- period.

Compare to Zombie Advocate, where someone fights for the rights of non-humans. This trope is about characters who despise those who would willfully hurt an animal. It can also be part of Even Evil Has Standards since for some, if the creature doesn’t have a say, they’re could be viewed as defenseless and would leave the animal alone. This is similar to Wouldn't Hurt a Child because of the same belief on never going after the weak.

There are some Truth in Television as some criminal organization does have rules regarding animals and won't tolerate those who are cruel to them. Animal Rights groups like PETA often advocates the end to the cruelty of animals.

Compare with Pet the Dog, where an anti-hero or villain does something good for society, perhaps making sure an innocent animal is out of harm's way.

Contrast with Kick the Dog...

Shoot the Dog, where someone is forced to a questionable act because it had to be done.

Anime/Manga

 * Elfen Lied: Lucy attacks a group of bullies for killing a puppy. The bullies did it out of pure amusement, only for them to learn it was Lucy's Berserk Button... the hard way.

Literature

 * The Berenstain Bears and the Bully: Sister Bear gets into a fight with Tuffy when she catches her attacking a baby bird.

Live-Action TV

 * The Blacklist: Raymond "Red" Reddington may still have villainous traits despite his willingness to reform, but even he has a soft-side for animals.
 * The Sopranos: Animal cruelty just so happened to be the Berserk Button of Tony Soprano. learns this one the hard way . For Tony,  Screw the money, he has rules.

Western Animation

 * The Simpsons: Lisa is a strict vegetarian, though in the video game version she does allow Bart to attack an army of Mutant Dolphin since it was on the grounds of defense.
 * Bart is the same way, but downplayed because he’s only cruel to insects. However, his Berserk Button includes anyone who dares harm any animals in his present that are above insects. Had he not been armed, Mr. Burns would’ve learned the hard way.
 * Doubled Subverted on Maggie in the film, where Krusty orders Mr. Teeny to go after her once they entered in the Simpsons’ house, only for Maggie to break a bottle in order to use as a weapon. She only backs on when Teeny runs back to Krusty.