system
Given the following post, respond as if you're commenting on Reddit:
human
Who is the Milton Friedman or Richard Feynman, of your field or area of study?

I wanted to know more people like these two gentlemen who are able to discuss complicated topics in layman's terms and/or make you see things in a different way. 
Edit: thank you for all the thoughtful responses. I wanted to clear the air on this question. The fact is that I left the question a little open to get your ideas and opinions. I want to learn both about people who have made great contributions to their respective fields and also about people who popularize their field. I think both ways are righteous because I doubt that there are many people like these two who have made great contributions, and have popularize their fields while doing so.
gpt
Robert Sapolsky in human behavioural biology / neuroendocrinology. His 'Human Behavioural Biology' course is on Youtube and utterly amazing. 

Daniel Kahneman's 'Thinking, fast and slow' is probably the best pop psych book written in decades.