Snakes
There are different types of snake species. Some of them contain deadly poison that can kill a human slowly or quickly. Others, like the Boa Constrictor, will simply strangle and crush its victims. And there are others like the Malayan Pit Viper whose venom isn’t generally fatal but can lead to tissue necrosis. If the person isn’t treated right away, the limb where they were bit might have to be amputated.