Chaim Ozer Grodzinski[1] (Hebrew: חיים עוזר גראדזענסקי; August 24, 1863 – August 9, 1940) was a Av beis din (rabbinical chief justice), posek (halakhic authority), and Talmudic scholar in Vilnius, Lithuania in the late 19th and early 20th centuries for over 55 years.

Chaim Ozer Grodzinski was born on 9 Elul 5623 (24 August 1863)[2] in Iwye, Belarus, a small town near Vilnius.

[4] He was a participant in the founding conference of Agudath Israel (in Kattowitz, Silesia, in 1912) and served on the party's Council of Sages.

[2] In 1909, there was a meeting in Hamburg, Germany, that was the precursor of Agudas Yisroel, whose main goal was to combat the Zionists and the Mizrachi against Zionism.

Other works include two collections of correspondences by Rabbi Grodzinski on more general communal and Hashkafic matters.