Gamaliel VI was the last Nasi of the ancient Jewish Sanhedrin. He was executed in 425 at the orders of the Eastern Roman Emperor Theodosius II for authorizing the building of new synagogues. Theodosius did not allow the appointment of a successor, thereby terminating the position. With him, therefore, the office expired. The office had already been robbed of its privileges by a decree of the emperors Honorius and Theodosius II (dated 17 October 415), after Gamaliel disregarded the discriminatory laws against Jews, built new synagogues, and adjudicated disputes between Jews and Christians.

Gamaliel appears to have been a physician. Marcellus, a medical writer of the fifth century, mentions a remedy for diseases of the spleen which had been discovered not long before by "Gamalielus Patriarcha."