Villains who abusively treat animals and/or another animal-like species or have no care that their actions can cause the extinction of an entire species. They can also be Poachers who are willing to hunt a rare animal.

It is the exact opposite of Animal Kindness.

Editing note: Do not add animals into this category (Unless in extreme cases and if the said animals are anthropomorphic) as animal-on-animal "cruelty" is normal and is a part of nature. (Like a lion fighting another lion for mating season or a shark eating a shoal of fish for survival) The latter should go under Predators instead because such acts are normal, no matter how "cruel" the animals may be.