The Klingon religious order that keeps the monastery on Boreth, where the faithful await the promised return of Kahless and the timekeepers guard the planet's time crystals.
Boreth is the world where Kahless promised to return, and its monks have kept vigil there for centuries. In The Next Generation episode Rightful Heir, Worf visits the monastery in 2369 seeking visions and sees Kahless apparently reborn. The high cleric Koroth and his fellows have in fact grown a clone from preserved blood and filled it with the sacred texts, and Gowron finally accepts the clone as a ceremonial emperor.
Discovery adds a second duty. In Through the Valley of Shadows, set in 2257, the monks are timekeepers who protect Boreth's time crystals. Their guardian Tenavik, the son of L'Rell and Voq aged by the crystals' influence, lets Christopher Pike take one only after Pike accepts a vision of his own crippling future.
Pike's later attempt to escape that fate, in the Strange New Worlds episode A Quality of Mercy, again involves the monks and their crystals.