Wilhelm Bacher (Hungarian: Bacher Vilmos; Yiddish: בִּנְיָמִין־זְאֵב בּאַככֿר, Hebrew: בִּנְיָמִין־זְאֵב בכר Benjamin Ze'ev Bacher; 12 January 1850 – 25 December 1913) was a Jewish Hungarian scholar, rabbi, Orientalist and linguist, born in Liptó-Szent-Miklós, Hungary to the Hebrew writer Simon Bacher. Wilhelm was himself a prolific writer, authoring or co-authoring approximately 750 works. He was a contributor to many encyclopedias, and was a major contributor to the landmark Jewish Encyclopedia throughout all its 12 volumes (Dotan 1977). Although almost all of Bacher's works were written in German or Hungarian, at the urging of Hayyim Nahman Bialik many were subsequently translated into Hebrew by Alexander Siskind Rabinovitz.
Wilhelm attended the Hebrew schools in Szucsány and in his native town, and passed through the higher classes of the Evangelical Lyceum at Presburg from 1863 to 1867, at the same time diligently prosecuting Talmudic studies.
In 1867 he began the study of philosophy and of Oriental languages—the latter under Ármin Vámbéry—at the University of Budapest, and also attended the lectures on the Talmud given by Samuel Löb Brill. In 1868, he went to Breslau, where he continued the study of philosophy and philology at the University, and that of theology at the Jewish Theological Seminary of Breslau. He graduated at the University of Leipsic in 1870. His graduation thesis, Nizâmî's Leben und Werke, und der Zweite Theil des Nizâmî'schen Alexanderbuches, appeared in 1871, and was translated into English in 1873 by S. Robinson. This was afterward incorporated in the collection entitled Persian Poetry for English Readers. In 1876, Bacher graduated as rabbi, and shortly afterward was appointed to the rabbinate in Szeged, which had become vacant in consequence of the death of Leopold Löw.