Columba of Rieti, TOSD was an Italian religious sister of the Third Order of St. Dominic who was noted as a mystic. She was renowned for her spiritual counsel, devotion to the Blessed Sacrament, and fantastic miracles were attributed to her. She was beatified by the Catholic Church in 1625.

The Third Order of Saint Dominic, also referred to as the Lay Fraternities of Saint Dominic or Lay Dominicans since 1972, is a Catholic third order which is part of the Dominican Order.