Lajos Blau (German: Ludwig Blau; April 29, 1861 – 1936) was a Hungarian scholar and publicist born at Putnok, Hungary. Blau was educated at three different yeshivot, among them that of Presburg. In 1880-1888, he was a student at the Rabbinical Seminary of Budapest (Landesrabbinerschule, now the Budapest University of Jewish Studies). At the same time, he studied philosophy and Orientalia at the Budapest University, received there the degree of Ph.D. cum laude in 1887, and the rabbinical diploma at the Seminary in 1888.
In 1887, Blau became a teacher of the Talmud at the Landesrabbinerschule, in 1888 a substitute, and in 1889 professor of the Bible, the languages of Hebrew and Aramaic, and the Talmud. Beginning in 1899, he became a librarian and tutor in Jewish history. In 1902, Blau became president of the folk-lore section of the Jewish-Hungarian Literary Society, and editor of the Magyar Zsido Szemle. He died in 1936.
Blau's scientific publications have dealt chiefly with the following topics:
Blau also published Der Concursus Vitiorum nach Talmudischem Recht, Budapest, 1887; and Die Erwählung Israel's (in Hungarian), ib. 1890; and contributed to the Monatsschrift, Zeitschrift für Hebräische Bibliographie, Jahrbuch des Ungarischen Litteraturvereines, Jahrbuch der Deutschen Litteraturvereines, etc.