Carlos Hugo, Duke of Parma and Piacenza (8 April 1930 – 18 August 2010) was the head of the House of Bourbon-Parma from 1977 until his death. Carlos Hugo was the Carlist pretender to the throne of Spain and sought to change the political direction of the Carlist movement through the Carlist Party, of which he was the official head during the fatal Montejurra Incident. His marriage to Princess Irene of the Netherlands in 1964 caused a constitutional crisis in the Netherlands.