Robert Ranulph Marett (13 June 1866 – 18 February 1943) was a British ethnologist. He was an exponent of what is sometimes called the Evolutionary School or more precisely the British Evolutionary School of Cultural anthropology. Founded by Marett's older colleague, Edward Burnett Tylor, it asserted that modern primitive societies evidence remnants of phases in the evolution of culture, which it attempted to recapture by comparative and historical methods. Marett focused primarily on the anthropology of religion. Asserting with Tylor the evolutionary origin of religions he modified Tylor's animistic theory to include the concept of mana. His anthropological teaching and writing career at Oxford University spanned the earlier 20th century prior to the Second World War. He trained many notable anthropologists.He was a colleague of John Myres and through him connected to the world of Aegean archaeology.
Marett was the only son of Sir Robert Pipon Marett, poet and Bailiff of Jersey, and Julia Anne Marett. He was born in Saint Brélade. He belonged to a family, originally named Maret, that settled on Jersey from Normandy in the 13th century. The Saint Brélade branch came finally to build a manor house for themselves, La Haule Manor (today a hotel). They were substantial in wealth and position, contributing high-level magistrates to the government of Jersey. Robert's father had been Bailiff of Jersey. He was one of the founders of La Patrie, a patriotic newspaper. Earlier, Philip Maret, 3rd son of the 2nd Seigneur of La Haule, born in 1701, had emigrated to Boston, where he became a merchant captain. His subsequent family participated in the American Revolution and the War of 1812.
Robert's mother, Julia Anne, also bore the name of Marett before marriage. She was one of the eight children of the Janvrin sisters, Esther Elizabeth and Maria Eliza, by one Philip Marett, who was not in Robert Pipon's immediate line. Philip was a name often used by the Maretts. Thus Julia Anne was only a distant cousin of her husband. The house, however, came into Robert Ranulph's possession through his mother. Her mother was Maria Eliza Janvrin. She and Robert Pipon had four children, Robert Ranulph, Mabel Elizabeth, Philippa Laetitia, and Julia Mary. Robert Ranulph may have been an only son, but he had three sisters and a large number of cousins. He came from a large-family environment. The family was Anglican. Cyril Norwood said of him, in a review of his autobiography in 1941: