Who, according to Jewish legends, was a one-day king of Poland?

Saul Wahl Katzenellenbogen (1541–1617) was a wealthy and politically influential Polish Jew who is said to have briefly occupied the throne of Poland on 18 August 1587. He has historically borne the nickname, "Le roi d'un jour" (king for a day). While no physical evidence exists to prove the veracity of the story that Saul was briefly king of Poland,[citation needed] it has nonetheless gained a firm place in the folklore of the Jewish people.