Pranciškus Petras Būčys (Polish: Piotr Franciszek Buczys, 20 August 1872 – 25 October 1951) was a Lithuanian Roman Catholic priest, university professor, titular bishop of the Eastern Catholic Church (consecrated in 1930), and Superior-General of the Congregation of Marian Fathers of the Immaculate Conception (1927–1933, 1939–1951). Born to a Lithuanian peasant family active in book smuggling, he studied at the Marijampolė Gymnasium and Sejny Priest Seminary and was active in Lithuanian cultural life. He started contributing articles to Lithuanian press, including Vienybė lietuvninkų and Varpa