Charles Darwin was the one who propounded the theory of evolution.  Theory of Charles Darwin has established the continuity between the animals and the man.  This theory has made and proved the importance of Comparative Psychology.

Anton Mesmer was the one who started the work of Hypnotism.

Sigmund Freud is the founder of Psychoanalysis which one of the branches of psychology.

William James was the Dean of the American Psychologists.

John Locke was the one who believed and established that the human mind at the time of birth is a tabularasa or most commonly known as blank slate.

Herman Ebbinghaus was known for his reported studies on learning and memory.

Alfred Binet was known for his work on the construction of test that measures the individual intelligence.