Jacob Saul Elyashar was a rabbi in the Land of Israel during the time of Ottoman rule. In 1893 he became the Sephardi Chief Rabbi among the Jews in Israel. Under the Ottomans (1517—1917) Israel was part of the province of Syria.
He was born in Safed to Eliezer Jeroham Elyashar. In 1853 he was appointed dayan in Jerusalem and became head of the beth din in 1869. In 1893 he became the Rishon LeZion or Sephardi chief rabbi of Palestine. Rabbi Shmuel Salant was the chief rabbi of the Ashkenasi community at the time and they enjoyed very warm relations and collaborated on various issues affecting the entire Jewish settlement in Palestine.
Rabbi Elyashar wrote thousands of responses to questions from Ashkenazim and Sephardim throughout the world.
The Jerusalem neighborhood of Givat Shaul is named after the Rabbi.