Medard Boss (October 4, 1903, St. Gallen – December 21, 1990, Zollikon) was a Swiss psychoanalytic psychiatrist who developed a form of psychotherapy known as Daseinsanalysis, which united the psychotherapeutic practice of psychoanalysis with the existential phenomenological philosophy of friend and mentor Martin Heidegger.
Also upon his return to Zurich, he trained at Burghölzli Hospital under the supervision of the psychiatrist Eugen Bleuler.
While at BPI he studied with Hanns Sachs, Otto Fenichel, Wilhelm Reich, and Kurt Goldstein.
He later went to London, where he worked closely with Ernest Jones for six months at the National Hospital for Nervous Diseases.
Back in Zurich he was invited by Carl Gustav Jung to join a workshop with other medical doctors to study analytical psychology, an experience that lasted nearly ten years and helped Boss to see that psychoanalysis need not be limited to Freudian interpretations.