Julius (Judah David) Eisenstein (November 12, 1854 – May 17, 1956) (Hebrew: יהודה דוד אייזנשטיין) was a Polish-Jewish-American anthologist, diarist, encyclopedist, Hebraist, historian, philanthropist, and Orthodox polemicist born in Międzyrzec Podlaski (known in Yiddish as Mezritch d'Lita), a town with a large Jewish majority in what was then Congress Poland.

Yehuda Dovid Eizensztejn, as he was named at birth, was the second of two children born to Rabbi Zeev Wolf and Toba Bluma (née Barg).

Her maternal grandfather, Rabbi Tzvi Zeev (in Yiddish, Hirsch Wolf) Fiszbejn, had already moved to Jerusalem with his two sons, Abraham and Isaac, and other descendants in 1863.

In HaModi'a laHadashim (New York) for 1901, he published, under the title LeDorot Golei Russiya b'America, a sketch of the history of Russo-Jewish emigration to America.

After arriving in Jaffa, he toured fledgling Zionist villages, including Rishon LeZion, Rehovot, and Petah Tikva, and reunited with his father in Jerusalem.

He visited Tel Aviv, Bnei Brak, and Petah Tikva, as well as the holy cities of Hebron, Tiberias, Safed, and Jerusalem, where he paid his respects at the graves of his father, great-grandfather, and great-uncles.

[5] Though Eisenstein became widely read as a writer, he was less successful as a businessman and lost much of his fortune in a failed effort to establish an agricultural colony for Jewish immigrants in New Jersey.

[1] Eisenstein and his wife, Rebecca (née Cohen), were the parents of nine children: Isaac (1875-1961), Nathan (1878-1952), Miriam (1882-1969), Lilly (1885-1916), Selig (1886-1978), Birdie (1888-1984), Rose (1891-1984), and Benedict (1894-1983).