Shammai (50 BCE – 30 CE, Hebrew: שַׁמַּאי, Šammaʾy) was a Jewish scholar of the 1st century, and an important figure in Judaism's core work of rabbinic literature, the Mishnah.

Shammai was the most eminent contemporary of Hillel. His teachings mostly agree with those of Hillel, except on three issues. Both were divided over an earlier rabbinic dispute, regarding the actual laying on of hands upon a sacrificial animal on a Festival Day, which Hillel permitted. Their disciples, who had differing views to their masters, disputed many other halakhic matters. The School of Shammai, founded by Shammai, is almost invariably mentioned along with the School of Hillel, founded by Hillel. They differed fundamentally from each other. Although they were contemporaries, Hillel was nearly sixty years old at the time of Shammai's birth.