Most Rev. Dr. Nicholas Donnelly (23 November 1837 – 29 March 1920), D.D., MRIA, was a Roman Catholic auxiliary bishop of Dublin. He was born in Dublin and educated at Castleknock College, before going on the Irish College in Rome. He was ordained a priest in 1860 and held various positions in the Dublin diocese, and in 1883 became an auxiliary bishop of Dublin and titular bishop of Canea (Crete). He also served as Parish Priest in Bray.
Rev. Donnelly was the author of a number of books, such as Short histories of the parishes of the Dublin diocese, as well as pamphlets and translations, such as a translation of Haberl's Magister Choralis. He contributed also to the Catholic Encyclopedia with an article on the Archdiocese of Dublin.
Donnelly had a keen interest in liturgical music and was a member of the Royal Irish Academy of Music, he was also a member of various societies such as the Royal Dublin Society, the Royal Irish Academy, the Royal Society of Antiquaries of Ireland, the Royal Societies Club (London) and the Dante Society of Ireland.
In 1882, on the death of his half sister Mary Boland (née Donnelly), he became guardian of her seven children, five girls and two boys, Patrick and John Pius Boland (who won two olympic medals in 1896 and became an MP for South Kerry). He was executor of her and her husband Patrick Bolands estate, which included the Boland's Bakery business, which he floated in 1888.
During the Royal visit of Queen Victoria to Ireland in 1900, Donnelly was present at a number of the events during her stay.
He died on 29 March 1920.