MICHAELSON, EZEKIEL ẒEVI BEN ABRAHAM ḤAYYIM (1863–1942), Polish rabbi, biographer, and bibliographer. He was a child prodigy, and in one of his works he cites responsa which he claims to have written at the age of 12. Orphaned in his early youth, he was forced to move from one place to another. In 1884 he was invited to become rabbi of the important community of Zamosc, but he refused. In the same year, he was elected rabbi of Karsinbrod. There he was harassed by enemies and was even arraigned in court as a result of a false accusation. In 1893 he became rabbi of Plonsk and from then on was known as "the rabbi of Plonsk." At the outbreak of World War I he was on a visit to Carlsbad and was unable to return home. In 1922 he was elected a member of the rabbinical council of Warsaw, and engaged in many communal activities. When the German forces entered Warsaw he was working in the community archives and in 1942 he was taken to *Treblinka where he died.
An exceptionally prolific writer whose knowledge of family lineages was unequaled, Michaelson published many books in such diverse fields as halakhah, aggadah, history, biography, and bibliography.
His best-known works are Degan Shamayim on tractates Berakhot and Rosh ha-Shanah (appended to Israel Jonah Landau, Ein ha-Bedolaḥ, 1901); responsa Beit Yeḥezkel, (1924); Pinnot ha-Bayit, novellae (1925); Siddur Beit ha-Oẓar (1931 (1929)); responsa Tirosh ve-Yiẓhar (1936). His most famous biographies are those of R. Israel Jonah of Kempen, R. Meshullam Zalman Ashkenazi, R. Joseph *Te'omim, R. Shabbetai *Bass, R. *Phinehas of Korets, the Margolioth family, R. Solomon *Ganzfried, R. Ẓevi Hirsh Ẓemah, and R. Jacob Aryeh of Radzymin, all appended to his editions of their works. During the Holocaust, three large chests containing his manuscripts were lost. They included Imrei Yeḥezkel on the Pentateuch and Me'at Ẓevi on the other books of the Bible.
N. Shemen, Di Biografie fun a Varshever Rov ha-Rov Ẓevi Yeḥezkel Michaelson (1948); Elleh Ezkerah, 2 (1957), 195–202.