John Dillon was an Irish politician from Dublin, who served as a Member of Parliament (MP) for over 35 years and was the last leader of the Irish Parliamentary Party. By political disposition, Dillon was an advocate of Irish nationalism, originally a follower of Charles Stewart Parnell, supporting land reform and Irish Home Rule.

The Irish Parliamentary Party was formed in 1874 by Isaac Butt, the leader of the Nationalist Party, replacing the Home Rule League, as official parliamentary party for Irish nationalist Members of Parliament (MPs) elected to the House of Commons at Westminster within the United Kingdom of Great Britain and Ireland up until 1918. Its central objectives were legislative independence for Ireland and land reform. Its constitutional movement was instrumental in laying the groundwork for Irish self-government through three Irish Home Rule bills.