Michel Matthew Ter-Pogossian (April 21, 1925 – June 19, 1996) was an American medical physicist.

He was professor of radiology at the Washington University School of Medicine for over 30 years. A pioneer in nuclear medicine, he is best known for his research on the positron emission tomography (PET). He is considered one of its creators and often referred to as the "father of PET."

Ter-Pogossian was born on April 21, 1925 in Berlin to Armenian parents from the Ottoman Empire that escaped the Armenian genocide. He was the only child. His family later moved to France, where Ter-Pogossian grew up. He developed an early interest in science and experimented with toy physics and chemistry kits as a child. Ter-Pogossian attended the University of Paris, from which he received his bachelor's degree in mathematics in 1942 or 1943. He subsequently studied at the Institute of Radium under Irène Joliot-Curie, graduating in 1946. He was active in the French Resistance during World War II.

Ter-Pogossian moved to the United States in 1946 to complete his studies. He preferred the US over Britain because the former seemed "more exciting."He enrolled at Washington University in St. Louis as a graduate student in 1946. He was drawn to the university by and studied under Arthur Compton, who was also the university's chancellor at the time.He simultaneously worked in the physics department as a research assistant. Ter-Pogossian received his master's degree in 1948, and his Ph.D. in nuclear physics from Washington University in 1950.

He joined the Mallinckrodt Institute of Radiology at Washington University in 1950. In the same year he also joined the faculty of Washington University School of Medicine as an Instructor in Radiation Physics. He was named professor of radiation physics in 1961, Professor of Biophysics in Physiology in 1964, and Professor of Radiation Sciences in 1973.

Between 1963 and 1991 Ter-Pogossian served as Director of the Division of Radiation Sciences at the Mallinckrodt Institute. After resigning from administrative duties in 1990, Ter-Pogossian devoted all his time to research. He was a self-proclaimed "research junkie". He became emeritus professor in 1995.

Ter-Pogossian was married to Ann (née Scott). They had two sons and a daughter. He was a resident of Clayton, Missouri. He traveled extensively and was a gourmet and a scuba diver. He was described by Ronald G. Evens as a "citizen of the world."

He died on June 19, 1996 of apparent myocardial infarction in Paris, where he was vacationing.