Leo Petrović (28 February 1883 – 14 February 1945) was a Bosnia and Herzegovina Franciscan and historian.
Petrović, a native of Klobuk, Ljubuški, entered the Franciscan Province of Herzegovina in 1900, and was ordained a priest in 1905. He held various monastic and ecclesiastical positions, including being a general vicar of the Diocese of Mostar-Duvno in 1943 and a Provincial of the Franciscan Province of Herzegovina from 1943 until 1945, when he was murdered by the communist Yugoslav Partisans. During World War II, Petrović helped Serbs, Jews and political dissidents, including the Yugoslav Partisans.
The first historian to rebuke the Bogomilist theory about the Bosnian Church, he promoted a thesis about the Bosnian Church having origins in the Catholic Benedictine monastic order, and that it used native language and observed the Roman Rite.
Petrović was born in Klobuk, Ljubuški in Bosnia and Herzegovina, at the time part of Austria-Hungary, into a family of Herzegovinian Croats, and was baptized as Grgo. His father was Marijan and mother Anđa, née Jurčić, from Pogana Vlaka near Grude. His parents were very religious Roman Catholics, but poor. He attended elementary school in Veljaci and Široki Brijeg, where he entered the Franciscan lower gymnasium in 1895, from which he graduated in 1900.
Petrović entered the novitiate of the Franciscan Province of Herzegovina on 4 October 1900 at the Franciscan friary in Humac, Ljubuški, and changed his name to Leo. After finishing his novitiate in 1901, Petrović started to study theology at the Franciscan Theological Seminary in Mostar, where he finished the first three years and the first half of the fourth year. He continued his education at the University of Fribourg in Switzerland in 1904. There, he took his monastic vows on 19 October 1904, and was ordained a priest on 30 July 1905. He celebrated his first Mass on 31 July in Klobuk. Under the mentorship of Prince Maximilian of Saxony, he earned his Ph.D., with a dissertation titled Disquisitio historica in originem usus Slavici idiomatis in liturgia apud Slavos ac praecipue Chroatos dissertatio on 31 January 1908. His dissertation was published later that year in Mostar.
Petrović was appointed professor of theology at the Theological Seminary in Mostar on 1 May 1907 and taught there until 8 May 1917. At the same time, from 1910 until 1916, he served as a secretary of the Franciscan Province of Herzegovina. During the Austro-Hungarian rule in Bosnia and Herzegovina, Petrović supported Croatian political alliance with the Serbs, contrasting the idea of Archbishop Josip Stadler.
He was appointed pastor in Klobuk on 8 May 1917, and remained there until 15 July 1919, when he was appointed guardian of the Franciscan friary in Mostar and a Dean of the Deanery of Mostar. After that, he was again appointed a professor at the Franciscan Theological Seminary in Mostar on 27 April 1925, where he lectured until 21 June 1926. The next day he was appointed a notary of the Bishop of Mostar-DuvnoAlojzije Mišić, where he served until 22 April 1943. On 23 April 1943, Petrović was appointed a diocesan general vicar, a post he held until 3 July 1943. From 1937 until 1943, Petrović was also an advisor to the bishop.