Shneur Zalman of Liadi

Shneur Zalman of Liadi, commonly known as the Alter Rebbe or Baal Hatanya, was a rabbi and the founder and first Rebbe of Chabad, a branch of Hasidic Judaism. He wrote many works and is best known for Shulchan Aruch HaRav, Tanya, and his Siddur Torah Ohr, compiled according to the Nusach Ari.