Justinus van Nassau (1559 – 1631) was the only extramarital child of William of Orange. He was a Dutch army commander known for unsuccessfully defending Breda against the Spanish, and the depiction of his surrender on the famous picture by Diego Velázquez, The Surrender of Breda. His mother was Eva Elincx, William's mistress between his first and second marriage. William of Orange recognized Justinus and raised him with his other children.