The Ruthenian Uniate Church was a particular church of the Catholic Church in the territory of the Polish–Lithuanian Commonwealth. It was created in 1595/1596 by those clergy of the Eastern Orthodox Church who subscribed to the Union of Brest. In the process, they switched their allegiances and jurisdiction from the Ecumenical Patriarchate of Constantinople to the Holy See.

Josaphat Kuntsevych, OSBM was a Basilian hieromonk and archeparch of the Ruthenian Uniate Church who on 12 November 1623 was beaten to death with an axe during an anti-Catholic riot by Eastern Orthodox Belarusians in Vitebsk, in the eastern peripheries of the Polish–Lithuanian Commonwealth.