Grete Anna Leutz is a German doctor, psychotherapist and founder of the Morenian Institute of psychodrama, sociometry and group psychotherapy in Überlingen near Lake Constance. She knew Moreno in the United States where she had moved, and where she was studying medicine. She was perfect to play the role of a "psychodrama sister" for the little Regina Moreno. She also deepened the techniques of role-playing and sociometry, both on the Beacon stage and on the domestic one, becoming a pioneer spirit in systemic approach and in psychotherapy of the family.
In 1973 Grete A. Leutz was one of the co-founders of the '' International Association of Group Therapy " – IAGP. From 1986 to 1989 she was also President. Besides teaching for ten years at the Medical School of Hannover, she also taught psychodrama therapy in Lindau and Lübeck for 30 years.