Reuvein Margolies, (Hebrew: ראובן מרגליות) (November 30, 1889 – August 28, 1971) was an Israeli author, Talmudic scholar and head of the Rambam library.
Margolies was born in 1889 in Lemberg (now Lviv), then part of the Austrian-Hungarian Empire and now in Ukraine and from 1918 to 1940 in Poland. After the passing of his wife, he emigrated to Israel in 1934, settling in Tel Aviv.
Margolies authored over 55 books on Jewish topics. He possessed a photographic memory, and was well versed in all aspects of both the written Bible, Oral Torah (Talmud and its commentaries) and Kabbalah (Zohar etc.). He established the Rambam library.
He wrote on a wide range of subjects, including on the Kabbalah.
He was also involved in a controversy with Gershon Scholem over the Rabbi Jacob Emden/Rabbi Jonathan Eybeshuetz controversy.
He wrote a number of scholarly biographies of major Jewish personalities such as Maharsha, Ohr Ha-Chaim Hakodosh, Noam Elimelech, Rabbi Moses ben Nachman (Ramban), and Rabbi Yechiel of Paris.
There is also a memorial volume edited by Dr. Yitchak Raphael and published by Mossad R' Kook, which describes these and more books in more detail.