R. Mordecai Solomon b. Isaac Friedman (1891-1971), Admor of Boyan, emigrated to New York in 1927 and established his dynasty on the Lower East Side. His piety, scholarly repute, and wit earned him a large following. He established the Ruzin Yeshiva which boasted many noteworthy scholars. The Rebbe was a founding member of the Agudat Israel in New York and heavily involved in community affairs.

R. Elijah Meir Bloch (c. 1894–1955), Lithuanian rabbi and dean of the Telz (Telshe) Yeshivah in the U.S., was born and educated in Telz, Lithuania. He was appointed to the faculty of the yeshivah there in 1917. With the Russian occupation of Lithuania, the yeshivah was moved to Cleveland, Ohio, in 1941, under R. Bloch's leadership. R. Bloch retained the singular "Telz style" in Talmud study, which stresses precise inductive reasoning. He resisted every attempt at compromise with the Reform elements of the community, yet succeeded in obtaining the support of the Cleveland Jewish Federation for the local Orthodox high school. Active with the Agudat Israel since the Marienbad Conference of 1937, and played a leading role in the American Agudah. He was also a member of Mo'ezet Gedolei ha-Torah, the international body which guides the World Agudah on questions of Torah principle, where he was known for the universality of his approach.

R. Menahem Zevi Eisenstadt (d. 1966), Polish rabbi. Born in Warsaw, Eisenstadt studied in Brisk, Lithuania, under R. Ḥayyim Soloveitchik and his son, R. Isaac Ze'ev. For a while he served as a member of the Cracow City Council. At the beginning of World War II, Eisenstadt moved to Vilna, where he directed the exiled Yeshivat Ḥakhmei Lublin. In 1941 he immigrated to Ereẓ Israel and lived in Tel Aviv. In 1947 he moved to the United States. In New York, he began the publication of an edition of Nahmanides' biblical commentary, based on early manuscripts and early editions. His work was not completed, however, and only the commentary to Genesis appeared (2 vols. 1959–62). He died in New York, and was buried in Jerusalem.

R. Moshe Sherer (d.1998). Charismatic president of Agudas Israel, he shaped and sustained one of the most vital and vibrant organizations in Torah communities in America. He was a master conciliator who forged lifesaving bridges among disparate groups. With indomitable spirit, he fought for Klal Yisroel's religious and civil rights, and reparations for Holocaust victims.

Michael (Mike) Tress (1909-1967) was the leader of Agudat Israel of America for many years during the twentieth century. He developed it from a small group to a major organization almost single handedly. He sold his business to help pay for the needs of the organization. His life and work are the subject of a book, They Called Him Mike, by Jonathan Rosenblum, Artscroll Publications.