The Order of Saint Basil the Great, also known as the Basilian Order of Saint Josaphat, is a Greek Catholic monastic order of pontifical right that works actively among Ukrainian Catholics and other Greek-Catholic churches in central and Eastern Europe. The order received approbation on August 20, 1631, and is based at the Monastery of the Holy Trinity, Vilnius.

Monastery of the Holy Trinity is a monastery built in Vilnius by the Ruthenian Church and Grand Hetman of Lithuania Konstanty Ostrogski as a thanksgiving to the God for the victory in Battle of Orsha. It now belongs to the Order of Saint Basil the Great and the Ukrainian Greek Catholic Church.