John James Brennan (Irish: Seán Séamus Ó Braonáin) (28 November 1887 – 11 October 1943) was a famous Irish sportsman who played hurling with Kilkenny. In a senior inter-county career that lasted from 1905 until 1914, he won four All-Ireland titles and four Leinster titles.
He was successful also in playing rugby, winning the Leinster Junior Cup with Kilkenny in 1920.
Brennan was a doctor who worked in Kilkenny, as a ship's surgeon with the Cunard Line on the Mauretania, and later in London, before returning to Kilkenny, where he died in 1944.
