Jacob Pavlovich Adler (Yiddish: יעקבֿ פּאַװלאָװיטש אַדלער; born Yankev P. Adler; February 12, 1855 – April 1, 1926) was an American actor and star of Yiddish theater, first in Odessa, and later in London and in New York City's Yiddish Theater District.

Nicknamed "Nesher haGadol" (Hebrew: הנשר הגדול, "the Great Eagle", Adler being the German for "eagle", and the nickname also refers to Maimonides), he achieved his first theatrical success in Odessa, but his career there was rapidly cut short when Yiddish theater was banned in Russia in 1883. He became a star in Yiddish theater in London, and in 1889, on his second voyage to the United States, he settled in New York City. Adler soon started a company of his own, ushering in a new, more serious Yiddish theater, most notably by recruiting the Yiddish theater's first realistic playwright, Jacob Gordin. Adler scored a great triumph in the title role of Gordin's Der Yiddisher King Lear (The Jewish King Lear), set in 19th-century Russia, which along with his portrayal of Shakespeare's Shylock would form the core of the persona he defined as the "Grand Jew".

Nearly all his family went into theater; probably the most famous was his daughter Stella, who taught method acting to, among others, Marlon Brando.