I would first decide like what kind of genre and type of personality you’re looking for. Then I’d Google “famous…. &&&s from history” like inventors, or military leaders, or doctors, etc. to find available choices. You could also search for “notorious” for people who aren’t totally good, or “unsung / uncredited” for people who did great achievement but never got credit or fame. You get the idea. Narrow down what you’d like first, because otherwise there’s seriously too much to choose from.