John Butler, 12th Baron Dunboyne

John Butler, 12th Baron Dunboyne (1731 – 7 May 1800) was an Irish clergyman and aristocrat, Roman Catholic Bishop of Cork and Ross. In order to advance his temporal title and marry he became, , the only authenticated apostate in the Catholic hierarchy in Ireland

Early life Butler was the third son of Edmond Butler, 8th Baron Dunboyne (died 1732) and the widow Anne Nagle, née Grace. He returned to Ireland in 1758, having completed his doctorate, though his Catholic credentials entailed an interview before a Justice of the Peace in Whitehaven. Butler returned to the Roman Catholic Archdiocese of Cashel and Emly, being appointed parish priest of Ardmayle in 1759. While he was establishing his place in the Church hierarchy, becoming an archdeacon and secretary to the bishop, he was also bolstering his secular role in the Butler family network.

Stole fees and other dues were resented and sometimes provided a pretext for Whiteboy violence towards the clergy. Butler issued a declaration, Statuta synodalia pro dioecesi Corcagiensi (1768), that involvement in the Whiteboys was a reserved sin. He supported the Test Act 1774 and gave substantial financial backing to the Catholic Committee. He took the oath of allegiance, abjuration, and supremacy. ensued before a compromise between the college and the family in 1808. The compromise led to the Dunboyne establishment at the college to endow scholarships.