Jules Isaac (18 November 1877 in Rennes – 6 September 1963 in Aix-en-Provence) was "a well known and highly respected Jewish historian in France with an impressive career in the world of education" by the time World War II began.
Internationally, Isaac was most well known for his tireless work after the Second World War in the field of Jewish-Christian relations, starting with his book Jésus et Israël, which was written during the war and made him a protagonist in the Seelisberg Conference of 1947, culminating in his decisive key role in the origin of the groundbreaking declaration Nostra Aetate during the Second Vatican Council. In the 1950s, Isaac had an international reputation for his work in Christian and Jewish relations.