Aharon Lichtenstein was an Orthodox rabbi and rosh yeshiva who was an authority in Jewish law (Halakha).

A rabbi is a spiritual leader or religious teacher in Judaism. One becomes a rabbi by being ordained by another rabbi—known as semikha—following a course of study of Jewish history and texts such as the Talmud. The basic form of the rabbi developed in the Pharisaic and Talmudic eras, when learned teachers assembled to codify Judaism's written and oral laws. The title "rabbi" was first used in the first century CE. In more recent centuries, the duties of a rabbi became increasingly influenced by the duties of the Protestant Christian minister, hence the title "pulpit rabbis", and in 19th-century Germany and the United States rabbinic activities including sermons, pastoral counseling, and representing the community to the outside, all increased in importance.