St. Teresa of Avila, also known as St. Teresa of Jesus, was a Spanish mystic, writer, and reformer of the Carmelite order in the 16th century. She is considered one of the most significant figures in the Catholic Church and is known for her spiritual writings, particularly her autobiography "The Life of St. Teresa of Avila." St. Teresa was a prominent advocate of contemplative prayer and inner spiritual experiences. She was canonized as a saint by the Catholic Church and is revered for her contributions to Christian mysticism and spirituality.