Shemtob Gaguin(e) (5 September 1884 – 30 July 1953) was a Sephardic rabbi and scion of a famous Moroccan rabbinical dynasty which emigrated to Palestine from Spain at the time of the Inquisition.

At an early age, he contributed articles to the Palestinian Hebrew Press (Hahhabbezeleth et al.) on aspects of Jewish traditional observances, as well as on biblical and philological matters.

He was awarded rabbinical diplomas by numerous authorities, including R. Haim Berlin and Chief Rabbis Jacob Meir, C.B.E.

He was also served as a Senior Rabbi to Lauderdale Road synagogue in Maida Vale of the Spanish and Portuguese Jews Congregation of London.

His major contribution to Jewish scholarship was Keter Shem Tob, an encyclopaedic treatise which examines and compares the rites, ceremonies and liturgy of the eastern and western Sephardim and Ashkenazim, paying particular attention to the customs of Spanish and Portuguese Jews.