Sigmund Freud and Charles Darwin cannot be left off the list of top influential people who wrought change. With his analysis of dreams as a method to crack the human psyche, Freud was much ahead of his time. Also, his contention that repressed carnal desires in the psyche are responsible for much of the adults' actions was a monumental inroad in clinical psychology. His psychoanalytical theory of the Id, Ego, and Superego is one of the most influential theories of modern times.
Another extremely influential theory is modern times is that of Charles Darwin, whose theory of evolution and its basic mechanism, Natural selection, has greatly changed people's thinking about many issues in human behavior.