Catherine of Siena was a 14th-century Italian mystic and theologian, born in 1347. She is best known for her deep spiritual writings and her role in the Catholic Church, advocating for reform and unity during a time of political turmoil. Catherine was a member of the Third Order of Saint Dominic and dedicated her life to serving the poor and sick. In 1376, she played a significant role in persuading Pope Gregory XI to return the papacy to Rome from Avignon. Catherine was canonized as a saint in 1461 and is recognized as a Doctor of the Church, highlighting her influence on Christian spirituality and theology.