Many people across the world have contributed to psychoanalysis in one way or another. Some are very well known, others less so, and many are largely forgotten. Colleagues in the field have begun to systematically collate details of the lives and professional biographies of key contributors. Notable among these has been Brigitte Nölleke, whose coverage of the lives of women who have contributed to psychoanalysis is second to none (see her Psychoanalytikerinnen). Richard Klein's ongoing project The Names of the Analysts is another very useful source, particularly for those interested in psychoanalytic genealogies (see the latest version of Richard's project and much else here). The present Who's Who is our attempt to collate brief lives mostly of the early contributors to psychoanalysis (here defined as those who began practising or otherwise contributing prior to World War II). It is an evolving work and here (as elsewhere) we welcome contributions that will extend or correct what we have begun.