António Nunes Ribeiro Sanches (7 March 1699 – 14 October 1783) was an 18th-century Portuguese physician, philosopher and encyclopédiste.

He was a cristão novo of Jewish descent, believed to be secretly a practising Jew.

After more than 15 years in Russia, he left the country in 1748 after empress Elizabeth Petrowna had denounced two of his colleagues as Jews.

Having had the chance, amid the daily proscriptions which he witnessed to be allowed to leave the country, he took the way to Paris in 1748 where he ended his life.

After she ascended to the throne, Catherine the Great rewarded him for his services with a pension of 1000 rubles, which was punctually paid until his death.