Created By: Jay P Hailey sourced from Worlds of the Federation (LUG Trek)
Number of Members: Up to 20,000
Nature of Members: Betazoids who have strong telepathic gifts, and a desire to help Betazoids live up to the burden of their gifts.
Organization: Hierarchical, based on the old Betazoid temple.
Game Role: To lead NPCs into adventures concerning the ethics of telepathy. (In pursuit of criminal Betazoids in space it is not unusual for Betazoid Priests to request Starfleet Aid.)
World Role: To enforce Betazoid telepathic morals and to help mentally ill Betazoids recover from their illnesses
Relative Influence: On Betazoid, large, in the Federation, they are a Planetary Law Enforcement service, but they approach interstellar matters hesitantly and so don't have as much influence as the V'Shar or Earth's Policia Mundial
Public or Secret?: Public, well known on Betazed, as the best of the best, not so well known off Betazed
Publicly Stated Goal: To ensure that all Betazoids use their gifts appropriately, ethically and to the betterment of all people. To Help sick Betazoids find their way back to Sanity, to capture and imprison Betazoid Criminals who's crimes involve gross telepathic misconduct or are infamous and heinous.
Relative Wealth: Good. They can afford all the common Law Enforcement gear.
Group advantages: They have the force of Betazoid law behind them. They can request help from Allied Federation law Enforcements and planetary authorities and usually get it.
Contacts: The Betazoid Priesthood has contacts with their analogous organizations through the Federation, as well as the Federation Bureau of Investigation, and Starfleet.
Special Abilities: The Betazoid Priesthood Recruits the strongest of Betazoid telepaths and trains them in cunning techniques of telepathic defense and, for lack of a better term, judo. They regularly cross train with members of other telepathic species, and have picked up a number of interesting tricks from all across known space.
Group disadvantages: They are relatively few in a galaxy of trillions, and their mission is split between being a Law Enforcement entity and a mental health entity.
Special Disadvantages: The Betazoid Priesthood bends over backwards to uphold the Betazoid ethical code to the very letter which means that they often self limit to the point where their own telepathic gifts are next to useless. (How ever, they have also picked up many tricks from non-telepathic law enforcement agencies.)
       Betazed still has the remains of historical nobility, many of whom feel that they are above the common Betazoid or Betazoid law. These are some of the most intractable offenders among the Betazoids.
Who belongs? Any Betazoid with sufficient telepathic strength, who feels called to such a degree as to undergo the demanding training and the strict discipline of the Betazoid Priesthood. Candidates are trained to be the equivalent of Psychologists and FBI agents, although duties are often specialized. There are a handful of Non-Betazoid Priests, but this is very, very rare.
Those who favor them: Betazoids who believe in Law and Order and Ethics, neighboring races who like the idea of unethical Betazoid eavesdroppers being carted away in chains.
Those opposed to them: Betazoids who use their gifts profligately, and without proper concern for the rights of others. Telepathic criminals who enjoy telepathically raping and torturing their way across Betazed and known space.
Area of Operation: Betazed Primarily. The Federation as whole secondarily.
Headquarters Location: Medara, the Capital City of Betazed
Public Face: Dour, professional priests who know what you're thinking, so you'd better not try it.
Notable Members: Crella Zolan, a priestess who, after a violent confrontation with a mind Criminal had to have her Larynx rebuilt. As she recovered she discovered she had a talent for singing, and now is a popular jazz singer, as such things go.
History of the Group: In the ancient past, the gods gave the Betazoids the gift of telepathy. In time, a religion sprang up concerning this. Legends still circulate about Khrysaros, the ancient Betazoid hero who defeated shadowy evil telepaths and gave the code of the Betazoids to his followers.
       For a long time Betazed was a theocracy, based on this religion but during the reformation of Dainara the Betazoid church stepped back from governing, turning power over to secular authorities.
       The First Betazoid interstellar contact was with the Terabians. After 100 years of contact and what the Betazoids thought was a happy relationship, the Terabians turned on the Betazoids viciously, causing the first Betazoid interstellar war.
       In the end it was discovered that profligate and casual use of telepathy by the Betazoids sparked huge resentments. The Betazoid religious view that telepathy was a blessing and therefore more powerful telepaths were more blessed also was less than charming to the mostly psi-null Terabians.
       After the war ended, the Betazoid Priesthood underwent a drastic reorganization and refocused on a new mission, keeping Betazoids from abusing each other and others with their gifts, spreading an ethical code of behavior about such gifts and heading off another resentment born war like the one with the Terabians.
       The Priesthood now asserts that more powerful Betazoid telepaths are more powerfully called to be of service to Betazed and sentient life in the galaxy.
       On the surface of Betazed, the Betazoids tend to be libertine and free with their telepathic gifts among each other. The Priesthood has it's work cut out for it training Betazoids how not to come off as snotty and stuck up about it, and how to be joyfully of service to their neighbors.

Jay's Note - these people were inspired by the LUG Source Book "Planets of the UFP" A very nice piece of world building. However the Betazoid priesthood and it's role in trying to enforce Betazoid ethics is not mentioned in the original article. I made that up