Darío del Niño Jesús Castrillón Hoyos was a Colombian cardinal of the Catholic Church. He was Prefect of the Congregation for the Clergy from 1996 to 2006 and President of the Pontifical Commission Ecclesia Dei from 2000 until his retirement in 2009. He was made a cardinal in 1998.

The Dicastery for the Clergy, formerly named Congregation for the Clergy, is the dicastery of the Roman Curia responsible for overseeing matters regarding priests and deacons not belonging to religious orders. The Congregation for the Clergy handles requests for dispensation from active priestly ministry, as well as the legislation governing presbyteral councils and other organisations of priests around the world. The Congregation does not deal with clerical sexual abuse cases, as those are handled exclusively by the Dicastery for the Doctrine of the Faith.