John Watson is know as the founder of Behaviorism. Watson published a manifesto titled "Psychology as the Behaviorist Views It." Watson believed the view that psychology should be concerned only with the objective data of behavior. Also one of Watson's main focuses was the concept of stimulus and response. .
There is no main founder of biological psychology. The history of this psychology dates back to ancient Greece. This kind of psychology focuses on the bases for behavior. These include the study of neuroanatomy and physiology, the influences of hormones and other chemicals both endogenous and exogenous, and the genetics and heritability of behavioral traits (Kalat, 1995, p55).
The two main founders of cognitive psychology are George Miller and Ulric Neisser. Miller wrote Language and Communication in 1951 and opened The Center for Cognitive Studies. Neisser was a Harvard grad with a Pd.D. in Psychology. He wrote two books, Cognitive Psychology and Cognition and Reality (Cognitive Processes Classes, Fall, 1997).
The major founder of humanistic psychology is Abraham Maslow. He wrote over 25 books about the subject, Motivation and Personality , being the most famous( www.maslow.com) Maslow's ideas of self-actualization and being needs set the basis for Humanistic psychology.
Another major founder of humanistic psychology is the late Carl Rogers. He revolutionized psychotherapy with his concept of "client-centered therapy." His influence has spanned decades, and has also become a major part of mainstream psychology today.
The primary founder of existential, also known as phenomenological, psychology is Rollo May. May, who was an American, is best known for his work on our struggles in living in the modern world. To successfully handle the trials of life, we must come face to face with such issues as anxiety, loneliness, choice and responsibility. May wrote five books on the subject, The most famous book being Love and Will.