Rabbi Shimon Gershon Rosenberg, ( ????? ????? ??????? ) (13 November 1949 - 11 June 2007), known by the acronym ??? ??"? HaRav Shagar, was a Torah scholar and a religious postmodern thinker.
His thought was characterized by Neo-Hasidism and postmodernism.
In 1996 he established Yeshivat Siach Yitzchak, in Efrat and was the head of the establishment until his death.