Rafael "Ka Paeng" Vitriolo Mariano (born October 24, 1956) is a Filipino politician.
He was a member of the House of Representatives for Anakpawis serving from 2004 to 2013.
He is also the chairman of the farmers militant group Kilusang Magbubukid ng Pilipinas (KMP).On May 31, 2016, after being nominated by the National Democratic Front, it was announced that Mariano will be joining the Cabinet of President Rodrigo Duterte as Secretary of the Department of Agrarian Reform.
He assumed the secretaryship on June 30, 2016 replacing Virgilio de los Reyes.
His appointment as Secretary of Agrarian Reform was rejected by the Commission of Appointments on September 6, 2017 making him the 4th member of the Duterte Cabinet to be rejected by the CA, after former foreign secretary Perfecto Yasay Jr., former environment secretary Gina Lopez, and former social welfare secretary Judy Taguiwalo.