Israel Isserlin (ישראל איסרלן; Israel Isserlein ben Petachia; 1390 in Maribor, Duchy of Styria – 1460 in Wiener Neustadt, Lower Austria) was a Talmudist, and Halakhist, best known for his Terumat HaDeshen, which served as one source for HaMapah, the component of the Shulkhan Arukh by Moses Isserles. He is also known as Israel of Neustadt, Israel of Marpurk, Maharai
Even though Regensburg in Bavaria is often quoted in literature as Isserlein's birthplace it is now clear that he was born in the Styrian Maribor or Marburg an Drau, present-day Slovenia, in the last decade of the 14th century. As a son of R. Petachia of Maribor he came from a well-known scholarly family. His grandfather Rabbi Chaim, named Henschel of Hainburg or Hetschlein of Herzogenburg was well-versed in Jewish learning, which held especially for Isserlein's great-grandfather R. Israel of Krems. R. Shalom of Neustadt was related to him.
He is considered to be the most influential rabbi of the Empire in the 2nd third of the 15th century and the last great rabbi of medieval Austria. With his wife Schoendlein he had four sons named Petachia (Kachil, Khatschel), Abraham, Shalom, Aaron, and a daughter Muscat, who died in her childhood.
After an early death of his father, it appears, he and his mother moved to Krems, where his uncle R. Aron Bluemlein of Krems/Vienna was teaching, and was together with his mother a victim of Viennese Gzerah in 1421. He studied also in Vienna and in Eger and probably also in Italy.
Soon after the Gzerah he returned to Maribor, where he started to serve as a rabbi and already in 1425 his correspondence and socializing with other scholars of his age is attested. Such a scholar was, for instance, Anshel of Maribor (Anshel Marpurk). His authority also included ordination of other rabbis. Responsa of rabbis Israel Bruna, Moses Mintz and Jacob Moelin or Maharil of Mainz quotes Isserlein with great respect. From an unknown reason he moved to Neustadt, where he is attested in 1445, even though due to the fact that he frequently traveled between Maribor and Neustadt, we can assume that he actually took residence in Neustadt around 1450. He dealt with money-lending only marginally and with small sums of money. In Neustadt, as before in Maribor, he started to run a yeshiva until 1460, when he died. Because of his activities he is also named R. Israel Marpurk and R. Israel of Noyshtat. On many occasion he signed as 'The small one and the young one in Israel' (Ha-katan ve-ha-tzair she-be-Israel).