The Talmud speaks of the Tzadikim Nistarim, 36 hidden righteous ones who prevent the world from falling apart. This is connected with the story of Sodom and Gomorrah, where God promises not to destroy the cities if 50 good men could be found. "Nistarim" means concealed ones. They are spread around the world and do not know of each other's existence. They are supposed to have the virtue of humility ("anavah"), and therefore none of them would admit that they are one of the 36. When disaster threatens, they emerge from concealment to justify the purpose of humankind in God's eyes, and when the crisis is over, they return to anonymity. I first learned about this from Kim Stanley Robinson's novel "Ministry for the Future".