One of the most popular and controversial scientists of the 20th century, Hans Eysenck had a major impact on psychology and society. Who was this charismatic and sometimes divisive figure, and why is he so relevant to science in the 21st century? Hans Eysenck (1916 – 1997) was a key figure in psychology, and his legacy still provokes varied and passionate responses. With interests that ranged from personality and intelligence to sex and violence in the media, Eysenck was unafraid to tackle contentious subjects of social and political importance. In the centenary of Eysenck's birth, Philip Corr explores the life and research of this contradictory and intriguing psychologist. With access to some of the people that were closest to Eysenck during his lifetime, Corr considers the scientific and historical contexts and assesses the continuing relevance of Eysenck's work.