William II de la Marck (Lummen, 1542–Bishopric of Liège, 1 May 1578) (Dutch: Willem II van der Marck) is Lord of Lumey and initially admiral of the Gueux de mer, the so-called 'sea beggars' who fight the Eighty Years' War (1568–1648), together with, among others, William the Silent, Prince of Orange-Nassau.
He is the great-grandson of an equally notorious character, baron William de la Marck, nicknamed the "wild boar of the Ardennes".