Reo Franklin Fortune (27 March 1903–1979) was a New Zealand social anthropologist. Originally trained as a psychologist, Fortune was a lecturer in social anthropology at the Cambridge University, and a specialist in Melanesian language and culture. He was married to Margaret Mead, with whom he undertook field studies in New Guinea, from 1928 to 1935.
He is also known for his contribution to mathematics with his study of Fortunate numbers in number theory. Fortune provided significant insights into the consequences of matrilateral and patrilateral cross-cousin marriage in advance of work by Claude Levi-Strauss.
- "EBSCOhost Connection: `Being Honest to my Science': Reo Fortune and J.H.P. Murray, 1927-30(n1).". connection.ebscohost.com. Retrieved 2008-04-19.
- Adam, Kuper (1994). The Chosen Primate: Human Nature and Cultural Diversity. Harvard University Press. pp. 186–189. ISBN 0-674-12826-5.
- "Fortunate number". The Prime Glossary. Retrieved 2008-04-19.
- "Reo FORTUNE (1903-1979)", Canberra Anthropology 3:105-108.
Abrahams, R. and H. Wardle. 2002. "Fortune's Last Theorem" 23:1, 60-2