Robert Hamill Nassau (1835 – May 6, 1921) was an American presbyterian missionary who spent forty years in Africa.

On the instigation of the Presbytery of New Brunswick he joined the Presbyterian Board of Foreign Missions as a missionary, with his first posting being to the African island of Corisco.

Throughout his career he served as a missionary in many places: Benita; Belambla; Kangwe; Talaguga; Baraka (Libreville); and Batanga.

Nassau's first wife was Mary Cloyd Latta, a fellow missionary who died on Corisco in 1870.

They had three sons William Latta, George Paull and Charles Francis His second wife was Mary Brunette Foster (died 1884), with whom he had a daughter Mary Brunette Foster.