R. Yitzchak Elchanan Spektor

R. Yitzchak Elchanan Spektor (1817-1896), Chief Rabbi of Kovno (Kaunas) from 1864 until his death, was the leading Lithuanian posek of his generation and the de facto head of Russian-Polish Jewry. His responsa series Be'er Yitzchak and Nachal Yitzchak are central Acharonim halachic resources; he ruled on questions ranging from agunah cases (where his lenient flexibility saved thousands) to early-modern technological developments. RIETS — the rabbinical school of Yeshiva University in New York — is named after him (Rabbi Isaac Elchanan Theological Seminary).