John IV, Duke of Brabant

John IV, Duke of Brabant (Atrecht June 11, 1403 – April 17, 1427, Brussels) was the son of Antoine, Duke of Brabant and Jeanne de St. Pol. He succeeded his father in 1415, after his death at the Battle of Agincourt.

In 1418, he married Jacqueline, Countess of Hainaut, who saw in him a protector against the claims of her uncle John III. However, the marriage proved unhappy.

Jacqueline fled John in 1420, and the Estates of Brabant declared his brother Philip of St. Pol the "ruwaard" (regent). However, he returned and regainted the regency in 1421, and his expansion of city privileges (the "Nieuw Regiment") in 1422 undermined the support of Jacqueline. and he now joined the party of the Cods to make war upon his quondam wife.

This second resurgence of the Hook and Cod wars pitted Jacqueline, her third husband Humphrey, Duke of Gloucester, and the party of the Hooks, against the Cods, represented by a coalition of John IV, his cousin Philip the Good, and John III of Hainaut. The death of John III in 1425 allowed John IV to make good his claims to Jacqueline's territories (she being then a prisoner in Burgundian hands in Ghent), but the real power and the title of ruwaard went to Duke Philip. At his death, he was succeeded by his brother Philip.

In 1425, he founded the Catholic University of Leuven.