When you are playing somebody who did exist, and there is good source material on them, whether it is a biography or archives or experts, you would be stupid not to delve into them. But there is a point in the process where you leave the books alone, and instead, you focus on the script and creating your version.
Yes, both 'Being Human' and 'Outlander' are known for their loyal fanbases. The beauty of both of those jobs was that the characters were very removed from me. So I've been lucky to get off scot-free, without any strange encounters. The wigs, blood, and strange onscreen faces/voices - they haven't found their way into my day-to-day life. Yet.