How Did Shakespeare Come Up With His Ideas For All Of His Villains?

There is actually some speculation about whether Shakespear came up with anything on his own. While he is one of the greatest and most famous of all playwriters scholars are discovering that Shakespear's plays were not entirely his own. "Romeo and Juliet" for instance was a story that was told all over Europe and one that come people say was true and written multiple times before Shakespear. As for another one of his plays "The Taming of the Shrew" was not his at all. A play titled "A Taming of the Shrew" was written and performed before Shakespears yet he is given the credit for it. Not all of this writing has been proven as plagerism but they are being looked into. So either his inspiration for villians came from people he met or what he believed to be cruel (morality wise) or it came from fellow playwriters.