Isaac (Isaak) Hirsch Weiss, also Eisik Hirsch Weiss (Hebrew: יצחק הירש ווייס) (9 February 1815 – 1 June 1905), was an Austrian Talmudist and historian of literature born at Groß Meseritsch, Habsburg Moravia.
After having received elementary instruction in Hebrew and Talmud in various chadorim of his native town, he entered, at the age of eight, the yeshiva of Moses Aaron Tichler (founded at Velké Meziříčí in 1822), where he studied Talmud for 5 years. He then studied at home under a tutor, and later in the yeshiva of Trebitsch, Moravia, under Ḥayyim Joseph Pollak, and in that of Eisenstadt, Hungary under Isaac Moses Perles, returning to his home town in 1837.