בַּעַל שֵׁם טוב – Rabbi Israel ben Eliezer, also known as the Ba’al Shem Tov (BeShT), was the founder of ḥasidut (חסידות), the Hasidic movement. Born around 1700 in what is now Ukraine, the BeShT was orphaned at a young age and was adopted into a religious community in the borderlands between modern-day Poland and Ukraine. He quickly became a beloved teacher and was devoted to the young children of his school. He lived a humble rural life, though many renowned scholars traveled to become his disciples. He died in 1760, having left no written teachings. Only his oral teachings have been transmitted through the generations beginning with his students in the 18th century.
Read more in the Jewish Encyclopedia.