There have been three Baronetcies created for persons with the surname O'Neill, two in the Baronetage of Ireland and one in the Baronetage of the United Kingdom.

The O'Neill Baronetcy, of Upper Claneboys, was created in the Baronetage of Ireland on 13 November 1643 for Brian O'Neill. The title became dormant on the death of the seventh Baronet in 1799.

The O'Neill Baronetcy, of Killelagh in the County of Antrim, was created in the Baronetage of Ireland on 23 February 1666 for Henry O'Neill. The title was forfeited in 1691.

The O'Neill Baronetcy, of Cleggan in the County of Antrim, was created in the Baronetage of the United Kingdom on 17 June 1929. For more information on this creation, see the Baron Rathcavan

Baron Rathcavan

Baron Rathcavan, of The Braid in the County of Antrim, is a title in the Peerage of the United Kingdom. It was created in 1953 for the Unionist politician Sir Hugh O'Neill, 1st Baronet. He had already been created a Baronet, of Cleggan in the County of Antrim, in 1929...

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O'Neill Baronets, of Upper Claneboys (1643)

• Sir Brian O'Neill, 1st Baronet (d. 1670)
• Sir Brian O'Neill, 2nd Baronet (d. 1694)
• Sir Henry O'Neill, 3rd Baronet (c. 1674-1759)
• Sir Brian O'Neill, 4th Baronet (d. c. 1765)
• Sir Randall O'Neill, 5th Baronet (d. 1779)
• Sir William O'Neill, 6th Baronet (c. 1754-1784)
• Sir Francis O'Neill, 7th Baronet (c. 1730-1799)

O'Neill Baronets, of Killelagh (1666)

• Sir Henry O'Neill, 1st Baronet (1625-c. 1680)
• Sir Neill O'Neill, 2nd Baronet (c. 1658-1690)
• Sir Daniel O'Neill, 3rd Baronet (forfeited 1691)