Saint Euthymius of Tarnovo was Patriarch of Bulgaria between 1375 and 1393. Regarded as one of the most important figures of medieval Bulgaria, Euthymius was the last head of the Bulgarian Orthodox Church in the Second Bulgarian Empire. Arguably the best esteemed of all Bulgarian patriarchs, Euthymius was a supporter of hesychasm and an authoritative figure in the Eastern Orthodox world of the time.

The Bulgarian Orthodox Church, legally the Patriarchate of Bulgaria, is an autocephalous Eastern Orthodox jurisdiction based in Bulgaria. It is the first medieval recognised patriarchate outside the Pentarchy and the oldest Slavic Orthodox church, with some 6 million members in Bulgaria and between 1.5 and 2 million members in a number of other European countries, Asia, the Americas, Australia, and New Zealand. It was recognized as autocephalous in 1945 by the Ecumenical Patriarchate of Constantinople.