Simeon ben Azzai or simply Ben Azzai (Hebrew: שמעון בן עזאי) was a distinguished tanna of the first third of the 2nd century. His full name was Simon ben Azzai, to which sometimes the title "Rabbi" is prefixed. But, in spite of his great learning, this title did not rightfully belong to him, for he remained all his life in the ranks of the "talmidim" or "talmide hakamim" (pupils or disciples of the wise). Ben Azzai and Ben Zoma were considered in the tannaitic school-tradition as the highest representatives of this degree in the hierarchy of learning (Tosef., Ḳid. iii.9; Bab. Ḳid. 49b; Ber. Ḳid. 57b; Yer. Ma'as. Sh. ii.53d; Bab. Sanh. 17b).
Ben Azzai is especially named as an eminent example of a "pupil who is worthy of the hora'ah," of the right of independent judgment in questions of religious law (Hor. 2b). Ben 'Azzai stood in close relation to the leaders of the school of Jabneh. He handed down, "from the mouth of two-and-seventy elders," who were present on the occasion, a halakic decision, which was accepted in Jabneh on the day when Eleazar ben Azariah was elected president in the place of Gamaliel II (Yad. iv.2; Zeb. i.3); also another resolution of the same day, declaring the books Kohelet and Shir ha-Shirim to be as sacred as the other Scriptures, whereby the collection of the Biblical writings, or the canon, was officially closed (Yad. iii.5).