Stefan Yavorsky (Russian: Стефа́н Яво́рский, Ukrainian: Стефа́н Яво́рський), born Simeon Ivanovich Yavorsky (Russian: Симеон Иванович Яворский) (1658 – 8 December [O.S. 27 November] 1722), was an archbishop and statesman in the Russian Empire and the first president of the Most Holy Synod.
Yavorsky was born in Yavoriv in western Ukraine, near Lviv. He enrolled in the Kyiv-Mohyla Academy around 1673 and completed its course of study; in 1684 he traveled to Poland to continue his education, at which point he was compelled to join the Uniate church, as was common for Kievan students who wanted to study in the Polish-Lithuanian Commonwealth; he took the Uniate name Stanislav (Russian: Станислав). He spent five years abroad, studying philosophy in Lvov and Lublin and theology in Poznań and Vilnius, where he completed his education. In 1689 he returned to Kiev, broke from the Uniate church and returned to Eastern Orthodoxy. He took monastic vows under the name Stefan and settled at the Kiev Academy as a preacher and professor, being appointed prefect of the institution and in 1697 hegumen of the Nikolaevsky monastery (Russian: Пустынно-Николаевский монастырь). He also began to preach, which soon made him well known in Kiev. At the beginning of 1700 he visited Moscow on church business, and when the boyar Aleksei Shein died in February Patriarch Adrian commissioned him to give the eulogy, which attracted the attention of Peter I, who was so pleased he had Yavorsky remain in Moscow and ordered a position to be found for him, as a result of which he was made archbishop of Ryazan and Murom in April. When Adrian himself died in October, Yavorsky was appointed locum tenens of the patriarchal see. "Thus in the course of seven months Iavorsky ascended from the humble position of father superior to the highest office in the entire church. Iavorsky had never desired such an appointment and even attempted to avoid it, but Peter was unyielding [because] the prelate was not a progressive or a reformer, but he was an authoritative figure with a European education, of which there were still few in Russia".