Pontifex Maximus

The Pontifex Maximus, or High Priest(ess), is the highest-ranking priest(ess) of a deity. The Pontifex Maximus heads the College of Priests (Collegium Pontificum) for that particular deity, and is superior to all the other Pontifices (priests/priestesses) for the deity. The Pontifex Maximus usually also runs the largest or primary temple to the god, which for many deities is located in the city of Rome. The Pontifex Maximus is selected by the priests of the College, and serves in the High Priest role for life.
When it comes to matters of religion, such as rulings on doctrine or scriptural interpretations, the priests of the College will normally decide matters by consensus. However, the Pontifex Maximus has the authority to overrule them, as the High Priest is considered the absolute authority on the god's religion.  Only the Emperor is superior to the Pontifex Maximus - as the Emperor is the legal head of the entire Roman religion. In practice, this almost never happens, and the Emperor will generally defer to a Pontifex Maximus on matters pertaining to individual gods and goddesses.

Qualifications

The Pontifex Maximus must be a full member of the Collegium Pontificum for that deity, and must be an ordained priest for the deity.

Appointment

Elected by a majority vote of the sitting Collegium members.

Responsibilities

Convenes meetings of the Collegium. Nominates pontifices to fill vacancies in the Collegium. Chairs all meetings of the Collegium. Final authority on interpretation of divine scripture, oracular prophecy, and other religious information.

Grounds for Removal/Dismissal

It is nearly impossible to remove or dismiss a High Priest or High Priestess. These individuals are viewed as having been appointed by their deity. To remove them would risk angering the deity.

Type

Religious, Political

Form of Address

Your Greatness

Alternative Naming

High Priest

Source of Authority

The College of Priests

Length of Term

Lifetime

Reports directly to

Emperor