The Holy Monastery of Theotocos the Olympiotissa is a Greek Orthodox monastery in Elassona, Thessaly, Greece. Dedicated to the Transfiguration of Christ until the 18th century, it is now dedicated to the Dormition of Theotocos. Founded in the 14th century, it is one if the oldest monasteries of the area. The Monastery houses a museum of rare ecclesiastical objects as well as a rich library including 233 manuscripts and some 650 early printed books.