The O'Neill Baronetcy, of Upper Claneboys, was created in the Baronetage of Ireland on 13 November 1643 for Brian O'Neill, in consideration of the loyalty and courage he had shown at the Battle of Edgehill.
His son, the second Sir Brian, was a High Court judge under James II, one of the very few Roman Catholics to serve on the Irish Bench before the nineteenth century.
The title became dormant on the death of the seventh Baronet in 1799.
The O'Neill Baronetcy, of Killeleagh in the County of Antrim, was created in the Baronetage of Ireland on 23 February 1666 for Henry O'Neill.
The (Chichester) O'Neill Baronetcy, of Cleggan in the County of Antrim, was created in the Baronetage of the United Kingdom on 17 June 1929.