1. Smallfolk / Commoners
(Houses of Westeros/Independents)

... selling their swords. The Faith is filled with poor brothers and septons who have come from meaner existences. Similarly, the red priests of the Lord of Fire largely come from the commoners throughout ...

2. Pentos, Free City
(World of Westeros/Cities)

The square brick towers of Pentos were black silhouettes outlined against the setting sun. Dany could hear the singing of the red priests as they lit their night-fires, and the shouts of ragged children ...

3. Classes
(About Game of Thrones/Game Rules)

... called 'red priests,' due to the loose, crimson robes they wear. Very few are known to exist in Westeros. Spy In Westeros, where sword and shield rule, Spies are seen as loathsome, cowardly, and weak. ...

4. R'hllor
(Faiths of Westeros/Faiths of Westeros)

... of stone. Clergy of the R'hllor religion are called 'red priests,' due to the loose, crimson robes they wear. In the east, children are often given to temples of R'hllor to be raised into the priesthood. ...