This article highlights three animals that have gained notoriety for being some of the worst serial killers in history. The first animal discussed is the domestic cat, known for its instinct to hunt and kill small prey. The second animal is the chimpanzee, which has been known to engage in violent and aggressive behaviors towards other animals and humans. The third animal mentioned is the bottlenose dolphin, which has been observed killing other dolphins and even porpoises for reasons that are not fully understood. These animals have earned the title of "serial killers" due to their repetitive and deliberate killing of other creatures. Despite their cute and seemingly harmless appearances, these animals exhibit predatory behaviors that have earned them a place among the most notorious killers in the animal kingdom. The article serves as a reminder that even the most innocent-looking creatures can possess deadly instincts.