Tomas Saguitan Fonacier (December 25, 1898 – July 5, 1981) was a Filipino historian and educator. He is known for being the second Filipino chairperson of the University of the Philippines Department of History, and the first dean of the University of the Philippines Iloilo (now part of University of the Philippines Visayas), which he helped found. Notable among his academic works is research on Chinese history and Ilocano history in the Philippines. According to the National Historical Commission of the Philippines, Fonacier's public service at the university, which spanned more than six decades, is the longest on record in that country.[1]