Leo Reino Sario (18 May 1916 – 15 August 2009) was a Finnish-born mathematician who worked on complex analysis and Riemann surfaces.
After service as a Finnish artillery officer in the Winter War and World War II, he received his PhD in 1948 under Rolf Nevanlinna at the University of Helsinki.
[1][2] Sario moved to the United States in 1950 and obtained temporary positions at the Institute for Advanced Study,[4] MIT, Stanford University, and Harvard University.
He was the author or co-author of five major books on complex analysis and over 130 papers.
He supervised 36 doctoral students, including Kōtarō Oikawa and Burton Rodin.