Question: Who is the paternal grandfather of Aaron Twersky Of Chernobyl?
Answer: Menachem Nachum Twersky

Mordechai Twersky (1770–1837), known as the "Maggid" of Chernobyl, was a Ukrainian rabbi. The son of Rabbi Menachem Nachum Twersky of Chernobyl and the second rebbe of the Chernobyl Hasidic dynasty. (The family surname was originally spelled Twerski)