מהרי"ל

Yaakov ben Moshe Levi Moelin was a Talmudist and posek best known for his codification of the customs (minhagim) of the German Jews. He is also known as Maharil - the Hebrew acronym for "Our Teacher, the Rabbi, Yaakov Levi" - as well as Mahari Segal or Mahari Moelin. Maharil's Minhagim was a source of law for Moses Isserles’ component of the Shulkhan Arukh.