A monk is a member of a religious order, typically an individual who takes on vows and lives their life to rules decreed by their religion.

In Bajoran religion, Prylars were a type of monk. (DS9 novel: Avatar, Book One, et al.)

In 2361, the monks of the Marrayat monastery on Altair III were killed by rebels during a revolution. (TNG comic: "Friends and Other Strangers")

In 2369, an away team from the USS Enterprise-D encountered a group of monks from a Dracon monastery on the planet Riat. These monks had been poisoned by algae in their water supply which made them cannibalistic and more aggressive than usual. The monks attacked the away team, who only just escaped. Once the away team were rescued, Doctor Beverly Crusher was able to cure the monks of their ailment. (TNG comic: "Light of the Day")