Cheng Kun was one of the villains in Jin Yong's novels. He used to be a great scholar in Jianghu. Later, he became a villain because he had a conflict with two other great scholars. His methods were cruel, and he often used all kinds of methods to achieve his goals, including assassinations, kidnappings, and killing innocent people. Therefore, some people thought that Cheng Kun was one of the most vicious villains in Jin Yong's novels. However, this conclusion might vary from person to person because everyone's definition and understanding of viciousness were different.