Mary, Untier of Knots or Mary, Undoer of Knots is the name of both a Marian devotion and a Baroque painting which represents that devotion. The painting by Johann Georg Melchior Schmidtner, of around 1700, is in the Catholic pilgrimage church of St. Peter am Perlach, otherwise known as the Perlach Church, in Augsburg, Bavaria, Germany. Devotion to the image had been limited to certain countries in Latin America but became known worldwide since the 2013 election of Pope Francis.

Mary, the mother of Jesus in Christianity, is known by many different titles, epithets, invocations, and several names associated with places.