Hans Jürgen Eysenck

German-born British psychologist (1916–1997), a leading 20th-century researcher in personality and intelligence. Developed trait theories (extraversion, neuroticism, psychoticism) and the Eysenck Personality Questionnaire; longtime professor at King's College London. Prolific and influential but also a controversial figure for his views on heredity of intelligence and for disputed research on smoking and cancer.