5. John Stuart Mill (IQ: 200)
John Stuart Mill is a British economist, logician and philosopher. He was one of the most important liberal thinkers in 19th century. Mill was a strong proponent of utilitarianism; an ethical theory developed by Jeremy Bentham. Along with Karl Marx, John Stuart Mill is considered one of the most important pioneers of modern economic theories. He developed a logic system for making proper transition from empiricism to contemporary logic and pragmatism. Mill was often considered as a man of extreme simplicity and his theories are still discussed in classes today.