Mariano Fazio is an Argentine Roman Catholic priest who is the Auxiliary Vicar of the Prelature of Opus Dei (2019 to the present). He was born on April 25, 1960 in Buenos Aires, Argentina . He was the rector of the Pontifical University of the Holy Cross from 2002 to 2008, and was the president of the Conference of Rectors of the Pontifical Universities of Rome. He served as the Regional Vicar of Opus Dei in Argentina, Paraguay and Bolivia up to 2014. In 2007, he worked as an expert at the Latin American Bishops Conference in Aparecida, Brazil.