William Reeves (16 March 1815 – 12 January 1892) was an Irish antiquarian and the Church of Ireland Bishop of Down, Connor and Dromore from 1886 until his death. He was the last private keeper of the Book of Armagh and at the time of his death was President of the Royal Irish Academy.
Born at Charleville, County Cork, on 16 March 1815, Reeves was the eldest child of Boles D'Arcy Reeves, an attorney, whose wife Mary was a daughter of Captain Jonathan Bruce Roberts, land agent to the 8th Earl of Cork. This grandfather had fought at the Battle of Bunker's Hill, and Reeves was born at his house in Charleville.
From 1823, Reeves was educated at the school of John Browne in Leeson Street, Dublin, and after that at a school kept by the Rev. Edward Geoghegan. In October 1830, he entered Trinity College, Dublin, where he quickly gained a prize for Hebrew. In his third year, he became a scholar and went on to graduate BA in 1835. He proceeded to read medicine, won the Berkeley Medal, and graduated MB in 1837. His object in taking his second degree was that he intended to become a clergyman and to practice the medical profession among the poor of his parish.
In 1838, he was appointed Master of the diocesan school in Ballymena, County Antrim, and was ordained a deacon of Hillsborough. The next year, he was ordained a priest of the Church of Ireland at Derry.
In 1844, Reeves rediscovered the lost site of Nendrum Monastery when he visited Mahee Island in Strangford Lough, County Down, searching for churches recorded in 1306, and recognised the remains of a round tower.