Byrne, Denis (d. 1744), priest, may have been born in Dublin, although little or nothing is known of his birth, parentage, or early career. He came to prominence in the early 1720s as curate to the controversial Cornelius Nary (qv). As a consequence of Nary's many commitments and intrigues, the running of the important parish of St Michan's largely devolved on Byrne. His appointment as dean of the chapter of the see of Dublin bore out his growing importance, although his promotion was deeply unpopular within the diocese.
Byrne undoubtedly owed his elevation to his mentor Nary, and he took every opportunity to repay his debt. He continually supported Nary's numerous attempts to influence both Rome and the Stuart court in relation to episcopal appointments, and signed (23 November 1728) a supplication with Nary and a group of Dublin clergy to thwart the appointment of Joseph Walsh as coadjutor of the archdiocese of Dublin. His name headed a petition (dated 28 August 1729) to the Stuart court in favour of the candidacy of Stephen McEgan, bishop of Clonmacnoise, for the vacant see of Dublin. However, this was rejected in favour of a compromise candidate, Luke Fagan (qv), bishop of Meath.
In 1739 Byrne spent a short time in Rome as agent of the Irish bishops. En route he had availed himself of an extensive catholic network which brought him to St John's coffee-house in London, Temple Mont-Saint-Justin in Paris, Brussels, and St Anthony's in Louvain. In Rome he was preoccupied with the two main concerns of the Irish mission: the recent founding of the protestant charter-schools, and the role of the Irish college in Rome in Irish ecclesiastical politics.
Byrne succeeded Nary as parish priest of St Michan's in 1738, where he remained until his death in 1744. As sole executor of Nary's will he inherited a house owned by Nary in Capel St., which he probably held in trust for his successor.