Pope Paul VI
Pope Paul VI knew the Roman Curia well, having worked there for a generation from 1922 to 1954. He implemented his reforms in stages, rather than in one fell swoop. On 1 March 1968, he issued a regulation, a process that had been initiated by Pius XII and continued by John XXIII. On 28 March, with Pontificalis Domus, and in several additional Apostolic Constitutions in the following years, he revamped the entire Curia, which included reduction of bureaucracy, streamlining of existing congregations and a broader representation of non-Italians in the curial positions.

Q: For whom did Paul VI work for from 1922 to 1954?
Roman Curia