Infante John, Constable of Portugal (Portuguese: João, Portuguese pronunciation: [ʒuˈɐ̃w̃]; Santarém, 13 January 1400 – 18 October 1442, Alcácer do Sal) was a Portuguese infante (prince) of the House of Aviz, Constable of Portugal and master of the Portuguese Order of St. James (Santiago). In Portugal, he is commonly referred to as the O Infante Condestável ("the Constable Prince").