The Pope

The Pope is the Bishop of Rome and the leader of the worldwide Catholic Church. He is the head of state of the Vatican.

Plot
When the Lvellier announces to Komui that he will make public the Allen Walker's case and decide his fate, Komui asks if this is a decision from the Pope. Lvellie doesn't answer.

When the Third Exorcist Program successfully produced half-Akuma species (Madarao, Tewaku, Tokusa, Kiredori and Goushi being the first results), Renny Epstain told Komui that the Pope himself ordered to put these five in service as the new Exorcists of the Black Order.

When Allen Walker and the Noah escape the cell of the Order, the Pope adressed his command about the situation to the whole Order (namely, about cancelling Allen's rights as an exorcict and classifying him as a Noah).