Fr. James Rupert Russell Mawdsley is a Catholic priest, formerly of the Priestly Fraternity of Saint Peter (FSSP). Prior to seminary, he was a prisoner of conscience in Burma. He is a dual citizen of the United Kingdom and Australia.

From 2016 to 2022, Mawdsley was a Catholic priest of the Priestly Fraternity of Saint Peter (FSSP), having studied to become a priest at the FSSP seminary at Wigratzbad in Germany. He was ordained to the priesthood on 2 July 2016, and was assistant priest at St Mary’s Church, Warrington in Cheshire, England through October 2017. From November 2017 through August 2018, Mawdsley was assigned to the FSSP apostolate in Reading, Berkshire, where he served the Latin Mass centres of Bedford and Chesham Bois. In September 2018, Mawdsley was assigned to the FSSP apostolate in Vienna, Austria. From October 2020 until April 2021, Mawdsley was assigned to the FSSP apostolate in Cologne, Federal Republic of Germany.

In response to Pope Francis’ promulgation of his motu proprio Traditionis custodes on 16 July 2021 restricting the use of the traditional Mass and the 18 December 2021 clarification on its implementation released by Bishop Arthur Roche, prefect of the Congregation for Divine Worship and the Discipline of the Sacraments, Mawdsley informed his superiors in the FSSP of his intention to leave the Fraternity in order to be able to speak out against the motu proprio without fear of reprisal from Church authorities.