It is difficult to say who the most famous female psychologist is, as there have been many notable and accomplished women in the field of psychology.
Some notable examples include Sigmund Freud's colleague and collaborator, Sabina Spielrein, who made significant contributions to the field of psychoanalysis; B.F. Skinner, who developed the theory of operant conditioning; and Jean Piaget, who is known for his work on cognitive development in children.