Jacob Berab (Hebrew: יעקב בירב), also spelled Berav or Bei-Rav, known as Mahari Beirav (1474 – April 3, 1546), was an influential rabbi and talmudist best known for his attempt to reintroduce classical semikhah (ordination).

Berab was born at Maqueda near Toledo, Castilian Spain in 1474. He later became a pupil of Isaac Aboab. After the expulsion of Jews from Spain, he fled to Fez in Wattasid-ruled Morocco. The Fez Jewish community, consisting of 5000 families, chose him for their rabbi, though he was but a youth of eighteen. From there he went to Tlemçen, then the chief town of the Barbary states. There, the Jewish community consisting of 5000 families, chose him for their rabbi, though he was but a youth of eighteen. Evidence of the great respect there paid him is afforded by the following lines of Abraham Gavison quoted by Isaiah Berlin's Omer ha-Shikḥah: "Say not that the lamp of the Law no longer in Israel burneth! Jacob Berab hath come back—once more among us he sojourneth!"

It is not known how long Berab remained in Algeria; but before 1522 he was in Jerusalem. There, however, the social and economic conditions were so oppressive that he did not stay long, but went with his pupils to Egypt. Several years later (1527) Berab, now fairly well-to-do, resided in Damascus; in 1533 he became rabbi at Cairo; and several years after he seems to have finally settled in Safed, which then contained the largest Jewish community in Ottoman Syria. It was there that Berab conceived the bold idea which made him famous, that of establishing a central spiritual Jewish power.

Berab had a plan for the reintroduction of the old semikhah "rabbinic ordination". It is likely that his further plans included the reestablishment of the sanhedrin. Berab's model was the sanhedrin of tannaitic times which consisted of men who could trace their ordination back to Moses; yet for more than a thousand years no such men had existed, and the semikhah was lost.

According to Louis Ginzberg, Berab's undertaking was part of a larger Messianic vision. In this period, Ginsburg says,

the imaginative and sentimental persons thought that the promised Messianic time was approaching; they regarded their great sufferings as the process of purgation, as the חבלי משיח, the eschatologic "birth-throes," of the Messianic era". These hopes "afforded the right person an excellent opportunity to create for the Jews a recognized central authority, spiritual—and perhaps, in time, political—in character. There is no doubt that the man for the purpose was Berab; he was the most important and honored Talmudist in the Orient, and was endowed with perseverance amounting to obstinacy.

According to others, the purpose of Berab's plan was a resolution of certain halachic difficulties. In particular, there was a problem of Marranos returning to the Jewish faith, and in order to free them from divine punishment some rabbis of the Land of Israel considered applying to them the punishment of makkot, which can only be assigned by Sanhedrin. Jacob Berab writes about this problem in his Responsa.

Maimonides taught that if the sages in the Land of Israel would agree to ordain one of themselves, they could do so, and that the man of their choice could then ordain others. Although Maimonides' opinion had been opposed by Nahmanides and others, the scholars at Safed had confidence in Berab, and had no doubt that, from a rabbinical standpoint, no objection to his plan could be raised.