Peter Barnard Gruenberg, MD, a true Renaissance man who moved seamlessly between the worlds of medicine, music, and many hobbies, passed away peacefully at his home in Los Angeles, California, on December 27, 2025. He was 90 years old.

Born in New York on September 21, 1935, to Helen and Herbert Gruenberg, Peter moved to Los Angeles with his family as a young child. He graduated from Hollywood High School and attended Los Angeles Community College as a film student before deciding to become a doctor. He transferred to UCLA (A.B. '56) and was later accepted at Case Western Reserve Medical School. During a summer break in Los Angeles, Peter was introduced to Stefani "Stefi" Sosin. The two instantly hit it off and moved to Cleveland together so Peter could finish medical school.

In 1960, they married, wearing wedding rings Peter had fashioned himself out of gold in Max’s dental office (his father-in-law). After graduation, Peter and Stefi returned to Los Angeles, where Peter completed his residency in psychiatry at UCLA and established a prominent private practice in Beverly Hills that spanned several decades. For almost 60 years, they lived in their beloved home on Warner Avenue, where they raised two children and lived a full and happy life.

Over a distinguished career, Peter rose to the rank of Professor of Psychiatry at the UCLA School of Medicine. A recognized authority on professional ethics, he chaired ethics committees at the local and national levels and served as President of the Southern California Psychiatric Society and the Los Angeles Psychoanalytic Society. He was also a Senior Faculty member at the New Institute for Psychoanalysis and was honored with a Special Presidential Commendation from the American Psychiatric Association.

Peter was an early advocate for the protection of people with mental health issues and worked to bridge the gap between mental health and law enforcement. He served on the Los Angeles Police Commission Task Force on the Mentally Disabled and as a Commissioner of Emergency Medical Services for LA County. He didn't just study these systems; he lived them. As a Level I-D Reserve Deputy Sheriff for 15 years with the West Hollywood Sheriff’s Department, he served as a "street cop" on patrol and performed helicopter-based mountain rescue operations with the Emergency Medical Services Detail, earning a "Distinguished Expert" shooting award.

Peter was notorious for his many hobbies and pursuits, which he delved into with gusto. He was a man who possessed the uncanny ability to fix anything—from plumbing to electrical mysteries—for his family and his neighbors. He was a pilot who took to the skies in his own plane, a motorcyclist, a jogger, and an early adopter of personal computers in the 1970s. A world traveler, he explored Africa, Asia, (China, and Japan) and Europe. He was a baker of bread, a brewer of beer, and an adventurous cook who apprenticed in local restaurants; his culinary curiosity dated back to the 1950s when he became an early fan of sushi.

His life-long love of classical music and opera was central to his life. He played the French horn in the Santa Monica City College Symphony and spent countless hours tuned into KUSC. Even in his leisure, he was whimsical, often found flying kites in his front yard using a fishing pole. In his later years, he loved nothing more than spending time with his family, particularly his two granddaughters, who brought him immense joy.

Peter leaves behind his loving wife of 65 years, Stefi; his son David Gruenberg (and wife Anka); his daughter Beth Sosnow (and husband Jeffrey Sosnow); and two granddaughters, Abby and Stella Sosnow. He is also survived by his brother Daniel and his three children, and two half-sisters, Jill and Kate and half-brother, Joel.

Services will be held at Hillside Memorial Cemetery on Tuesday, December 30, at 10:00 am and reception at Noon at their home. 

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