Sigmund Freud was an Austrian neurologist and the founder of psychoanalysis.
Erich Fromm was a German-American social psychologist and philosopher who significantly impacted the fields of humanistic psychology and psychoanalysis, advocating for individual freedom and societal change.
Albert Ellis was an American psychologist and creator of Rational Emotive Behavior Therapy, a precursor to Cognitive Behavioral Therapy.
Aaron Beck was an American psychiatrist and psychotherapist, widely regarded as the father of cognitive therapy and a pioneer in the treatment of depression.