Anton Atanas Sielava (Belarusian: Антон Сялява, Ukrainian: Антін Селява, Polish: Antoni Sielawa) (1583 – 5 October 1655) was the Metropolitan of Kiev, Galicia and all Ruthenia in the Ruthenian Uniate Church — a sui juris Eastern Catholic Church in full communion with the Holy See. He reigned from 1641 until his death in 1655.