Final answer:
Sigmund Freud and the neo-Freudians were the main theorists behind the psychoanalytic theories.
Step-by-step explanation:
The main theorists behind the psychoanalytic theories were Sigmund Freud and the neo-Freudians. Freud, an Austrian neurologist, developed the theory of psychoanalysis, which emphasized the role of the unconscious mind and childhood experiences in shaping personality. Neo-Freudians like Alfred Adler, Erik Erikson, Carl Jung, and Karen Horney built upon Freud's work and focused more on the social environment and cultural influences on personality development.