Yaakov Hai Zion Ades (Hebrew: יעקב חי ציון עדס, February 24, 1898 – July 19, 1963),[1] also spelled Adas or Adess, was a Sephardi Hakham, Rosh Yeshiva, and Rabbinical High Court judge.

Upon his parents' aliyah to Israel in 1896, his father helped found Rechovot Hanahar, a yeshiva for kabbalists in the Bukharim quarter, and served on the beit din of the Aram Soba (Aleppo) community.

[6] He received his early education from his father, but at age 12 was sent to study in Yeshiva Ohel Moed under Rabbis Yosef Yedid Halevi and Shlomo Laniado.

[6][7] All of his unpublished Torah writings from that period were destroyed when the Jordanian Arab Legion set fire to the yeshiva during their occupation of the Old City in 1948.

[6][7] In 1935 Ades, then a senior maggid shiur at Yeshivat Ohel Moed, was offered a seat on the Sephardic Beit Din of Jerusalem by the Rishon Le-zion, Rabbi Yaakov Meir.

He would spend hours selecting his arba'ah minim (the Four Species of Sukkot), examining hundreds of hadassim until he found the one that met all halakhic requirements.

[1] His son Rabbi Yehuda Ades founded Yeshivat Kol Yaakov in the Bayit Vegan neighborhood of Jerusalem in his memory.