Joseph Patrick Brennan (10 September 1889 – 4 May 1968) was an Irish Clann na Poblachta politician and medical doctor.

He moved back from the US to his mother's native Knocknagoshel, County Kerry at around the age of six years.

During the civil war, a group of insurgents that included Brennan had occupied part of the Gresham Hotel in O'Connell Street and were holding out against the Free State army.

He was Vice President of the Irish Christian Front which held its inaugural meeting at the Mansion House, Dublin on 22 August 1936.

The Irish Independent invited the formation of a committee to make a decision to support pro-Franco citizens of Spain in their war effort.

[2] He presided over the International Congress of Catholic Doctors which took place at University College Dublin in 1954.