Chaim Volozhin (or Chaim Volozhiner or Chaim of Volozhin) (1749-1821) was an Orthodox Judaism rabbi, Talmudist, and ethicist. Popularly known as Reb Chaim Volozhiner, or simply Reb Chaim, he was born in Volozhin, near Vilna, Lithuania and died there.

One of the most prominent disciples of the Vilna Gaon, Reb Chaim Volozhiner established the Volozhin yeshiva . It endured for more than 100 years, becoming the "mother of all [[Lithuanian Jews|Lithuanian]-style yeshivas". He continued to teach the Vilna Gaon's study method of penetrating analysis of the Talmudic text, seeking to elicit the intent and meaning of the writing of the Rishonim - the pre-1550 commentators. This approach was followed by all the great Lithuanian yeshivas, such as Slobodka yeshiva, Mir yeshiva , Ponevezh yeshiva (Panevezys), Kelm yeshiva (Kelme), Klezk yeshiva , and Telz yeshiva (Telsiai).

His major work is known as the Nefesh HaChaim ("Spirit of Life"), a kabbalistic work, the purpose of which is "to implant the fear of God, Torah, and pure worship into the hearts of the upright who are seeking the ways of God." In addition he wrote Ruach Chaim, a commentary on Pirkei Avoth.