Modesto P. Sa-onoy (born July 4, 1938) is a Filipino historian and journalist specializing in the history of Negros Island in the Philippines.
He was born in La Castellana, Negros Occidental. He is an alumnus of La Consolacion College in Bacolod City, graduating there from high school in 1956, Bachelor of Arts in 1961, Bachelor of Science in Education in 1963 and Master of Arts in Education in 1965.
He has twice been President of the Negros Press Club, first in 1982-1983, second in 1989-1990. He is married to Ma. Verobina Abeto and has two children, Aufred Paul and Angela Rosario.
- Brief History of the Church in Negros Occidental, 1976
- Valderrama, 1978
- The Chinese in Negros, 1980
- The Dentists of Negros, 1981
- Negros Occidental History, First Edition, 1992
- Through the Years: History of La Consolacion, Bacolod, 1993
- A Glance at Bacolod, 1998
- Genealogy of the Marañon-Miraflores Family, 2002
- Occidental Negros History, Second Edition, 2003
- Genealogy of the Sa-onoy Family, 2004
- Ordeals of War (Ed.), 2006
- Parroquia de San Diego: 1776-2006, 2006