The Eastern Catholic clergy of the Ukrainian Greek Catholic Church were a hereditary tight-knit social caste that dominated Ukrainian society in Western Ukraine from the late eighteenth until the mid-twentieth centuries, following the reforms instituted by Joseph II, Emperor of Austria. Because, like their Eastern Orthodox brethren, married men in the Ukrainian Catholic Church could become priests, they were able to establish "priestly dynasties", often associated with specific regions, for many generations. Numbering approximately 2,000-2,500 by the 19th century, priestly families tended to marry within their group, constituting a tight-knit hereditary caste. In the absence of a significant culturally and politically active native nobility, and enjoying a virtual monopoly on education and wealth within western Ukrainian society, the clergy came to form that group's native aristocracy. The clergy adopted Austria's role for them as bringers of culture and education to the Ukrainian countryside. Most Ukrainian social and political movements in Austrian-controlled territory emerged or were highly influenced by the clergy themselves or by their children. This influence was so great that western Ukrainians were accused by their Polish rivals of wanting to create a theocracy in western Ukraine. The central role played by the Ukrainian clergy or their children in western Ukrainian society would weaken somewhat at the end of the nineteenth century but would continue until the Soviet Union forcibly dissolved the Ukrainian Greek Catholic Church in Ukrainian territories in the mid-twentieth century.

The Eastern Catholic Churches or Oriental Catholic Churches, also called the Eastern-Rite Catholic Churches, Eastern Rite Catholicism, or simply the Eastern Churches, are 23 Eastern Christian autonomous particular churches of the Catholic Church, in full communion with the Pope in Rome. Although they are distinct theologically, liturgically, and historically from the Latin Church, they are all in full communion with it and with each other. Eastern Catholics are a distinct minority within the Catholic Church; of the 1.3 billion Catholics in communion with the Pope, approximately 18 million are members of the eastern churches.