The Tzadikim Nistarim or Lamed Wufniks are a group of entities in Jewish folklore.
Description
There are thirty-six Tzadikim Nistarim in the world. They are scattered across the earth, and they do not know each other. A Nistarim is always a poor man, but they are regardless just and good. Although they do not understand their own importance, they are the protectors of the world. Their purpose is to prove the goodness in humanity; if it were not for them, God would destroy all of humanity. The Nistarim do not know what they are. If a man discovers that he is one of the thirty-six, he immediately dies and another replaces him.
Origin
This story originates from the Book of Genesis, in which God states that he would spare Sodom and Gomorrah if ten good men could be found in them.