Ona Šimaitė was a Lithuanian librarian at Vilnius University who used her position to aid and rescue Jews in the Vilna Ghetto during World War II. She is recognized as a Righteous Among the Nations.

Righteous Among the Nations is an honourific used by the State of Israel to describe all of the non-Jews who, for purely altruistic reasons, risked their lives in order to save Jews from being exterminated by Nazi Germany during the Holocaust. The term originates from the concept of ger toshav, a legal term used to refer to non-Jewish observers of the Seven Laws of Noah.