The Slovak Greek Catholic Church or Byzantine Catholic Church in Slovakia, is a sui iuris (autonomous) Eastern Catholic church based in Slovakia. As a particular church of the Catholic Church, it is in full communion with the Holy See. The church is organised as a single ecclesiastical province with one metropolitan see. Its liturgical rite is the Byzantine Rite. In 2008 in Slovakia alone, the Greek Catholic Church in Slovakia had some 350,000 faithful, 374 priests and 254 parishes. In 2017, the Catholic Church counted 207,320 Greek Catholics in Slovakia worldwide, representing roughly one percent of all Eastern Catholics.

The Ruthenian Greek Catholic Church, also known in the United States as the Byzantine Catholic Church, is a sui iuris (autonomous) Eastern Catholic church based in Eastern Europe and North America. As a particular church of the Catholic Church, it is in full communion with the Holy See. It uses the Byzantine Rite for its liturgies, laws, and cultural identity.