Fidel Ronquillo Nemenzo is a Filipino mathematician and professor who served as chancellor of the University of the Philippines Diliman from 2020 to 2023.

He chairs the Mathematics Division of the National Research Council of the Philippines, having been elected to the NRCP Governing Board in 2019.

[3] The son of Martial Law era activist and later University of the Philippines President Francisco Nemenzo Jr, he has himself had a long history of political activism.

A UP student leader during the time of martial law under Ferdinand Marcos, he was shot in the back during the infamous Welcome Rotonda rally shootings of September 27, 1984[7][8] and almost died from the single M-16 bullet that pierced through his body.

[11] On January 19, 2020, he spoke at the protest demonstration against the Department of National Defense (DND)'s unilateral termination of the 1989 UP-DND Accord which requires the police and military to notify UP officials before they enter UP campuses.