Msgr. Mariano Fazio currently serves as Vicar General of the Prelature of Opus Dei. An Argentinian, he was ordained a priest in 1991 by St. John Paul II.

He has been Rector of the Pontifical University of the Holy Cross in Rome, President of the Conference of Rectors of the Pontifical Roman Universities, and Regional Vicar of Opus Dei for Argentina, Paraguay and Bolivia. He is a historian and philosopher and has written several books of philosophical reflections on modern society and on secularization.