National University "Ostroh Academy" (Ukrainian: Національний Університет Острозька Академія, translit.: Natsional'nyi Universytet Ostroz'ka Akademiia) is a Ukrainian self-governed (autonomous) research university that was re-opened in 1994 by the Presidential Decree of April 12, 1994. The university was re-opened in place of a historical Ostroh Academy that was founded in 1576 in Ostroh by a Ruthenian nobleman Konstanty Wasyl Ostrogski. In 17th century all the universities of the Polish-Lithuanian Commonwealth got under influence of the Catholic or Protestant nobles. To counter this influence Count Konstanty Ostrogski, one of the most influential people in the Crown of Poland and a major partisan of the Orthodox faith, founded a large university-like school in his estate in Ostrog in what is now Ukraine. Ostrogski envisioned a lay academy, that would however strengthen the Orthodox spirit in the country and prevent mass conversions to Protestantism, Greek or Latin Catholicism, a process in full swing at the time. and as such was first mentioned in Piotr Skarga's 1577 On the Unity of God's Church under a Single Shepherd and on Greek Dismissal of this Union.